Review of the current objectives and modern approaches to studying extant and extinct shrews (Soricomorpha: Soricidae) investigation: the origin of the modern subfamilies and diversity of Crocidosoricinae

The current review is devoted to topical issues of the origin of modern shrew’ subfamilies Soricinae Fischer, 1817 and Crocidurinae Milne-Edwards, 1868 (Soricomorpha: Soricidae), as well as to the consideration of the possibility of using morphological analysis to search for ancestral groups of modern soricine and crocidurine shrews within the extinct subfamily Crocidosoricinae Reumer, 1987. The data on the taxonomic composition of the Crocidosoricinae subfamily and the preliminary results of a comparative analysis of the Neogene shrews Miosorex Kretzoi, 1959 and Shargainosorex Zazhigin et Voyta, 2018 (Crocidosoricinae) shrews with the representatives of Soricinae and Crocidurinae according to the shape of the first upper molar M1 are presented as an example to substantiate urgent problems in this area. The problem of relations of molecular and morphological data are discussed using individual groups as examples. Modern approaches of geometric morphometry are described, which together with phylogenetic data allow assessing the expression of the phylogenetic signal when analysing the shape of morphological structures. Possible prospects for the practical application of these approaches for the study of fossil material and the search for ancestral lineages of modern shrews among Crocidosoricinae are described.

Multi-Modal Oral Implantology. The Screw-Blade Single-Implant for the Replacement of the Upper Molar: A Case Report

Intense forces are naturally downloading on molar roots. Due to inflammation, the post-extraction sockets of the upper molars are often poor of bone on one side. A single implant supporting a prosthetic crown can easily go subject to displacing forces that reabsorbed and recently healed bone can hardly bear. By utilizing a couple of prosthetic roots, i.e.: one screw implant in the side in which bone is richer and one blade implant in the side in which the bony wall has gone subject to reabsorption, it is possible to build a better supported prosthetic crown. The clinical cases performed by the Authors confirm the validity of this implant architecture. Aim of the work is to describe a post-extraction multi-modal implantological technique useful for replacing the roots of upper molars with poor bone support on one side. Materials and Methods: Combination of submerged screw implant and submerged blade implant or emergent screw implant and emergent blade implant welded intraorally. Discussion: The combination of a palatal screw implant and a buccal blade implant, or vice versa, allowed to solve clinical cases and to make reliable prosthetic crowns. Conclusions: The presence of variable residual anatomies in the molar area of the upper jaw recommends the use of morphologically different implant shapes, suitable for the construction of a biomechanically functional prosthetic abutment. Specifically in the presence of bone resorption, the combination of a screw implant and a blade implant allowed us to obtain a reliable abutment. Given the small number of cases performed, further research will confirm the positive results of this technique.

Sex and age differences in skull size in Myodes glareolus from Slovakia

The results of a craniometric analysis of the bank vole (Myodes glareolus) were evaluated in this study. Twenty cranial variables were measured and evaluated on 149 skulls (78 males, 71 females) with respect to sex and age. The main aim of this study was to test the sexual dimorphism in skull size. Overall, our results showed that on average, the values for adult and subadult females of M. glareolus were higher than for males. Results presented here thus reveal sexual differences in the measured cranial traits, most expressed for the length of the mandible and the height of the mandible. The effect size was very large for the length of the first upper molar. Comparison of our results with those from other countries confirmed that there are regional differences. These findings highlight the need for craniometric analysis of species also at the regional level.

First molar extractions related to molar-incisor hypomineralization (MIH) in a special need patient: case report

Although most orthodontists avoid extractions, treating patients with biprotrusion traditionally involves removing teeth. In the current case report, a 15-year-old deaf patient had a Class II molar and canine relationships, 8 mm overjet and 3mm overbite, 3 mm of a discrepancy between U/L midline, crowding in both arches (3 mm in the upper and 7 mm in the lower). The first right upper molar (16) and the first right and left lower molars (36 and 46) were severely MIH affected. Extraction of the first four molars was proposed, since a large amount of space was required and three of the four molars were very compromised with severe MIH. Tooth 26 was extracted to maintain the symmetry of the arch and because the extraction of a premolar would not allow for alignment associated with class II correction of canines on the left side. During the closure of the extraction spaces, upper and lower third molars eruption was observed, in an appropriate position. Facial analysis shows us the coincidence of the upper midline with the face and good exposure of the incisors in the smile. There was considerable reduction of overjet and dental protrusion, enabling passive lip sealing. A perfect fit of the Class I superior teeth was not obtained since the patient considered that the treatment was already very good and did not want to collaborate with hygiene and the use of orthodontic appliances for more time.

Effects of Variable Composite Attachment Shapes in Controlling Upper Molar Distalization with Aligners: A Nonlinear Finite Element Study

The objective of the present study is to describe the stress and displacement patterns created by clear aligners and composite attachments bonded with the acid-etch technique on the labial surface of the maxillary first upper molar during its distalization. Maxillary molar distalization is a clinical orthodontics procedure used to move the first maxillary molar distally. The procedure is useful in patients with some Class II malocclusion allowing the first molar to move into a Class I relationship and the correction of associated malocclusion features. Three finite element models were designed to simulate the alveolar bone, molar tooth, periodontal ligament, aligner, and composite attachments. The first model had no composite attachment, the second model had a vertical rectangular attachment, and the third model had a newly designed attachment. A loading method was developed that mimicked the aligner’s molar distal movement. PDL was set as a viscoelastic material with a nonlinear mechanical response. von Mises and maximum principal stresses and tooth displacement patterns were analyzed using dedicated software. All the configurations showed some form of clockwise rotation in addition to the distal movement. The crown portion of the tooth showed maximum displacement in all three models; however, in the absence of attachment, the root apex moved in the opposite direction which was compatible with uncontrolled tipping movement. Simulations with attachments exhibited the best performance regarding the movement patterns. The third group, with the newly designed attachment, exhibited the best performance concerning stress distribution (principal stress and von Mises stresses) and higher stresses in the periodontal ligament and tooth. Incorporating a vertical rectangular attachment in a clear aligner resulted in the reduction of mesiodistal tipping tendency during molar distalization. The third model was the most efficient considering both displacement pattern and stress distribution. The level of stress generated by the third model needs to be further investigated in future studies.

The Effect of Lipoteichoic Acid from Lactobacillus plantarum on Dental Pulp Inflammation

Objective Lactobacillus plantarum, a bacterium located in deep caries, has a virulence factor in the form of lipoteichoic acid (LTA), which is found in the bacterial cell wall. LTA is able to trigger a neutrophils response in the dental pulp inflammation process within the first 6 to 24 hours. The quantity of bacteria is one factor influencing the increase in number of neutrophils in addition to the quality of the bacteria. This study seeks to analyze the effect of lipoteichoic acid of Lactobacillus plantarum (LTA-Lp) in the dental pulp inflammation by observing the number of neutrophil cells in a histopathological view. Materials and Methods The LTA was isolated from L. plantarum. The left upper molar of Rattus novergicus was mechanically perforated under anesthesia to induce dental pulp inflammation. The perforated tooth was then induced by 10 and 15 µg/mL of LTA-Lp and then restored by a temporary filling. The perforated tooth in the control group was only restored by a temporary filling. After 24, 48, and 72 hours, the tooth was extracted and then stained with hematoxylins and eosin to observe the neutrophils in the dental pulp via a light microscope. Result The number of neutrophils in the dental pulp after induction by 15 µg/mL of LTA-Lp is higher than 10 µg/mL of LTA-Lp and both controls. There were significant differences in the number of neutrophils in the dental pulp, in each group on 24, 48, and 72 hours after LTA-Lp inducing (p < 0.05). Conclusion The LTA-Lp dose of of 10 and 15 µg/mL affected the dental pulp inflammation by affecting the number of neutrophils.

Manufacturing a First Upper Molar Dental Forceps Using Continuous Fiber Reinforcement (CFR) Additive Manufacturing Technology with Carbon-Reinforced Polyamide

3D printing is an emerging and disruptive technology, supporting the field of medicine over the past decades. In the recent years, the use of additive manufacturing (AM) has had a strong impact on everyday dental applications. Despite remarkable previous results from interdisciplinary research teams, there is no evidence or recommendation about the proper fabrication of handheld medical devices using desktop 3D printers. The aim of this study was to critically examine and compare the mechanical behavior of materials printed with FFF (fused filament fabrication) and CFR (continuous fiber reinforcement) additive manufacturing technologies, and to create and evaluate a massive and practically usable right upper molar forceps. Flexural and torsion fatigue tests, as well as Shore D measurements, were performed. The tensile strength was also measured in the case of the composite material. The flexural tests revealed the measured force values to have a linear correlation with the bending between the 10 mm (17.06 N at 5000th cycle) and 30 mm (37.99 N at 5000th cycle) deflection range. The findings were supported by scanning electron microscopy (SEM) images. Based on the results of the mechanical and structural tests, a dental forceps was designed, 3D printed using CFR technology, and validated by five dentists using a Likert scale. In addition, the vertical force of extraction was measured using a unique molar tooth model, where the reference test was carried out using a standard metal right upper molar forceps. Surprisingly, the tests revealed there to be no significant differences between the standard (84.80 N ± 16.96 N) and 3D-printed devices (70.30 N ± 4.41 N) in terms of extraction force in the tested range. The results also highlighted that desktop CFR technology is potentially suitable for the production of handheld medical devices that have to withstand high forces and perform load-bearing functions.

Developmental influence on evolutionary rates and the origin of placental mammal tooth complexity

Development has often been viewed as a constraining force on morphological adaptation, but its precise influence, especially on evolutionary rates, is poorly understood. Placental mammals provide a classic example of adaptive radiation, but the debate around rate and drivers of early placental evolution remains contentious. A hallmark of early dental evolution in many placental lineages was a transition from a triangular upper molar to a more complex upper molar with a rectangular cusp pattern better specialized for crushing. To examine how development influenced this transition, we simulated dental evolution on “landscapes” built from different parameters of a computational model of tooth morphogenesis. Among the parameters examined, we find that increases in the number of enamel knots, the developmental precursors of the tooth cusps, were primarily influenced by increased self-regulation of the molecular activator (activation), whereas the pattern of knots resulted from changes in both activation and biases in tooth bud growth. In simulations, increased activation facilitated accelerated evolutionary increases in knot number, creating a lateral knot arrangement that evolved at least ten times on placental upper molars. Relatively small increases in activation, superimposed on an ancestral tritubercular molar growth pattern, could recreate key changes leading to a rectangular upper molar cusp pattern. Tinkering with tooth bud geometry varied the way cusps initiated along the posterolingual molar margin, suggesting that small spatial variations in ancestral molar growth may have influenced how placental lineages acquired a hypocone cusp. We suggest that development could have enabled relatively fast higher-level divergence of the placental molar dentition.

Microsurgical endodontic treatment of the upper molar teeth and their relationship with the maxillary sinus: a retrospective multicentric clinical study

Purpose To assess the clinical and radiographic success rate of microsurgical endodontic treatment of upper molar teeth in relationship with the maxillary sinus, with 12 months follow-up. Methods Patients treated with microsurgical endodontic treatment of upper molar teeth in the period between 2017 and 2019 were recruited from two dental clinics according to specific selection criteria. The outcomes were determined based on clinical and radiographic results taken three, six and 12 months post-operatively, compared with those taken immediately before and after surgery. Clinical and radiographic outcomes were recorded. The distance between the most apical part of the root and of the lesion to the maxillary sinus was measured on CBCT images before the surgery. Patient-related outcomes were recorded. Results Out of 35 patients evaluated, 21 were selected according with the selection criteria for a total of 27 roots and 29 canals treated. After 12 months, 18 patients showed a complete healing whereas three demonstrated incomplete healing. Consequently, the success rate in this study was 85.7% after one year. In 28.5% (6 patients) there was a perforation of the Schneiderian membrane that didn’t seem to affect the outcome. All patients kept the molar one year later. The pain level decreased significantly over the time during the first week after surgery. Conclusion Microsurgical Endodontic treatment of the upper molar teeth should be considered a valid and predictable treatment option even in case of Schneiderian membrane perforation. Future clinical studies with a larger sample size are needed to compare the results obtained.