scholarly journals Post-natal Effect of Overexpressed DKK1 on Mandibular Molar Formation

2011 ◽  
Vol 90 (11) ◽  
pp. 1312-1317 ◽  
Author(s):  
X.L. Han ◽  
M. Liu ◽  
A. Voisey ◽  
Y.S. Ren ◽  
P. Kurimoto ◽  
...  
Keyword(s):  
Developmental Stages ◽  
Formation Rate ◽  
Third Molar ◽  
Nestin Expression ◽  
Second Molar ◽  
Mandibular Molar ◽  
Targeted Expression ◽  
Enamel Knots ◽  
Dentin Formation

Dickkopf-related protein 1 (DKK1) is a potent inhibitor of Wnt/β-catenin signaling. Dkk1-null mutant embryos display severe defects in head induction. Conversely, targeted expression of Dkk1 in dental epithelial cells leads to the formation of dysfunctional enamel knots and subsequent tooth defects during embryonic development. However, its role in post-natal dentinogenesis is largely unknown. To address this issue, we studied the role of DKK1 in post-natal dentin development using 2.3-kb Col1a1- Dkk1 transgenic mice, with the following key findings: (1) The Dkk1 transgene was highly expressed in pulp and odontoblast cells during post-natal developmental stages; (2) the 1st molar displayed short roots, an enlarged pulp/root canal region, and a decrease in the dentin formation rate; (3) a small malformed second molar and an absent third molar; (4) an increase of immature odontoblasts, few mature odontoblasts, and sharply reduced dentinal tubules; and (5) a dramatic change in Osx and nestin expression. We propose that DKK1 controls post-natal mandibular molar dentin formation either directly or indirectly via the inhibition of Wnt signaling at the following aspects: (i) post-natal dentin formation, (ii) formation and/or maintenance of the dentin tubular system, (iii) mineralization of the dentin, and (iv) regulation of molecules such as Osx and nestin.

The role of accelerated dental development on the occurrence of aberrant dental traits that indicate malocclusion

2018 ◽  
Vol 41 (4) ◽  
pp. 397-403
Author(s):  
Brunilda Dhamo ◽  
Amanda M Nguee ◽  
Edwin M Ongkosuwito ◽  
Vincent W V Jaddoe ◽  
Eppo B Wolvius ◽  
...  
Keyword(s):  
Developmental Stages ◽  
Dental Development ◽  
Dental Age ◽  
Second Molar ◽  
Logistic Regression Models ◽  
Tooth Impaction ◽  
Mandibular Teeth ◽  
Dental Traits ◽  
2D And 3D

Summary Background Timing of dental development might help orthodontists to optimize initiation of treatment and to prevent and intercept dental misalignment. This study examines the association between timing of dental development and aberrant dental traits such as crowding, impaction, and hypodontia. Methods This study was performed using 4446 ten-year-old children from a multiethnic birth cohort, the Generation R Study. Dental development was defined using the Demirjian method. Crowding, impaction, and hypodontia were ascertained from 2D and 3D pictures and radiographs. We built three series of logistic regression models to test the associations of dental age with crowding, impaction, and hypodontia. Similar models were built to investigate the associations of the developmental stages of each left mandibular tooth with crowding, impaction, and hypodontia. Results Inverse associations were found between every 1-year increase in dental age and the presence of crowding [odds ratio (OR) = 0.84, 95% confidence interval (CI): 0.79, 0.89], impaction of teeth (OR = 0.66, 95% CI: 0.52, 0.84), and hypodontia (OR = 0.52, 95% CI: 0.47, 0.56). Lower developmental stages of the second premolar were associated with the presence of crowding (OR = 0.90, 95% CI: 0.83, 0.98). Lower developmental stages of the second premolar (OR = 0.88, 95% CI: 0.79, 0.98), first molar (OR = 0.76, 95% CI: 0.65, 0.90), and the second molar (OR = 0.83, 95% CI: 0.73, 0.94) were associated with the presence of tooth impaction. Lower developmental stages of all mandibular teeth except the central incisor were associated with hypodontia (P < 0.05). Conclusion Accelerated dental development is associated with lower occurrence of crowding, impaction, and hypodontia.

scholarly journals PREDICTION OF EXTRACTION DIFFICULTY FOR INFERIOR THIRD MOLAR

InterConf ◽  
2021 ◽  
pp. 273-278
Author(s):  
Gabriela Motelica ◽  
Nicolae Chele ◽  
Sergiu Beliniuc
Keyword(s):  
Medical Records ◽  
Third Molar ◽  
Radiographic Examination ◽  
Common Complication ◽  
Correct Position ◽  
Anatomical Structures ◽  
Second Molar ◽  
Mandibular Third Molar ◽  
Mandibular Molar ◽  
The University

Inferior third molar impaction remains an actual topic of discussion in modern dentistry due to the frequent complications and treatment contraindications. According to Rock and Elsey inferior third mandibular molar impaction occurs in 73% of young people. Many theories of impaction of inferior 3rd molar have been proposed, but the most popular is the insufficient development of retromolar space. Some authors claim that M3 extraction should only be performed when complications may occur, others say that M3 should be extracted if there are no contraindications, but Martin Kunkel is the advocate of the prophylactic extraction of the inferior third molar. In order to achieve the proposed goal, the frequency of impaction of mandibular third molar and their relationship with neighboring anatomical structures was evaluated. There were statistically processed data of medical records and radiographic examination. This study was made based on 320 patients treated in the University Dental Clinic nr.2, SUMPh ,,Nicolae Testemițanu”. Of these, 147 patients were selected: 58 patients with impacted inferior 3rd molar and 89 patients with inferior 3rd molar apparently erupted in the correct position. The most common complication caused by M3 was pericoronitis, followed by second molar caries.

scholarly journals The role of impacted third molar angulation on the anterior crowding

2021 ◽  
Vol 11 ◽  
pp. 56-61
Author(s):  
Gökçenur Gökçe ◽  
Burçin Akan ◽  
Ilknur Veli
Keyword(s):  
Contact Point ◽  
Third Molar ◽  
Occlusal Plane ◽  
Third Molars ◽  
Second Molar ◽  
Anterior Crowding ◽  
The Third ◽  
Irregularity Index ◽  
3D Digital Models

Objectives: The aim of this study was to assess the role of impacted third molar angulation on the severity of anterior crowding. Materials and Methods: Panoramic radiographs and three-dimensional (3D) digital models of 45 patients satisfying the following inclusion criteria were selected for this study. To calculate the irregularity index of Little, the sum of the contact point displacements from the anatomical contact point to the contact point among the lower canine teeth was measured on 3D digital models. Little’s irregularity index was used to classify patients as having mild, moderate, or severe crowding. For intragroup variance, comparisons T test was used. The Spearman single rank correlation coefficients were used to analyze any correlation among degree of crowding and (a) third molar inclination to base of mandible, (b) third molar inclination to occlusal plane, and (c) third molar inclination to second molar inclination respectively. Results: There were no statistical differences found in all tested parameters (i.e., third molar inclination to mandibular plane, inclination of the third molars to occlusal plane, and inclination of the third molars to second molars) among three groups (P > 0.005). Conclusion: It can be deduced that no relationship obtains among the third molar inclination to base of mandible, third molar inclination to occlusal plane, third molar inclination to second molar inclination, and the level of anterior crowding.

scholarly journals Evaluation of autogenous tooth transplantation for replacement of the missing or unrestorable mandibular molar tooth

2017 ◽  
Vol 10 (2) ◽  
pp. 126
Author(s):  
Wahiduj Jaman ◽  
Shohda Khatun ◽  
Quazi Billur Rahman
Keyword(s):  
Third Molar ◽  
Molar Tooth ◽  
Second Molar ◽  
Tooth Transplantation ◽  
Arch Bar ◽  
Mandibular Molar ◽  
Long Term Observation ◽  
Missing Tooth

<p>This study was undertaken to evaluate the functional and occlusal stability of autogenous tooth transplantation. A total of 30 patients were included. Among them, 21 participants received transplanted first molar and the remaining 9 received transplanted second molar. In all the cases, donor tooth were third molar. In each participant, extraction of un-restorable first or second molar tooth was performed which was then replaced by atrumatic extracted third molar tooth. Each third molar tooth was placed in the recipient extracted socket, followed by the evaluation of the occlusion and then stabilized with arch bar and ligature wire. Clinical follow-up evaluation was performed at 15 days, 3 and 12 months in respect to occlusal stability, tooth mobility and periodontal status. It was found that 23 transplanted tooth were successful and the remaining 7 tooth need long-term observation for the final outcome, which was statistically significant. It can be concluded that the autogenous tooth transplantation can replace missing tooth to ensure the preservation of function, aesthetic and to prevent bone resorption of the missing area of the jaw, which can lead to exceptional esthetic and functional outcome.</p>

scholarly journals Crayfish hemocytes develop along the granular cell lineage

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Fang Li ◽  
Zaichao Zheng ◽  
Hongyu Li ◽  
Rongrong Fu ◽  
Limei Xu ◽  
...  
Keyword(s):  
Developmental Stages ◽  
Cell Lineage ◽  
Granular Cell ◽  
Marker Genes ◽  
Hematopoietic Tissue ◽  
Differentiated Cells ◽  
Stage Of Development ◽  
Almost All ◽  
Relationship Of

AbstractDespite the central role of hemocytes in crustacean immunity, the process of hemocyte differentiation and maturation remains unclear. In some decapods, it has been proposed that the two main types of hemocytes, granular cells (GCs) and semigranular cells (SGCs), differentiate along separate lineages. However, our current findings challenge this model. By tracking newly produced hemocytes and transplanted cells, we demonstrate that almost all the circulating hemocytes of crayfish belong to the GC lineage. SGCs and GCs may represent hemocytes of different developmental stages rather than two types of fully differentiated cells. Hemocyte precursors produced by progenitor cells differentiate in the hematopoietic tissue (HPT) for 3 ~ 4 days. Immature hemocytes are released from HPT in the form of SGCs and take 1 ~ 3 months to mature in the circulation. GCs represent the terminal stage of development. They can survive for as long as 2 months. The changes in the expression pattern of marker genes during GC differentiation support our conclusions. Further analysis of hemocyte phagocytosis indicates the existence of functionally different subpopulations. These findings may reshape our understanding of crustacean hematopoiesis and may lead to reconsideration of the roles and relationship of circulating hemocytes.

scholarly journals Assessment of the Retromolar Canal in Taiwan Subpopulation: A Cross-Sectional Cone-Beam Computed Tomography Study in a Medical Center

Tomography ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 219-227
Author(s):  
Yen-Wen Shen ◽  
Wan-Chun Chang ◽  
Heng-Li Huang ◽  
Ming-Tzu Tsai ◽  
Lih-Jyh Fuh ◽  
...  
Keyword(s):  
Medical Center ◽  
Third Molar ◽  
Mandibular Canal ◽  
Cone Beam ◽  
Horizontal Distance ◽  
Taiwanese Population ◽  
Mandibular Bone ◽  
Second Molar ◽  
The Third ◽  
Retromolar Canal

The retromolar canal is an anatomical variation that occurs in the mandibular bone. The retromolar canal typically originates in the mandibular canal on the distal side of the third molar and extends forward and upward to the retromolar foramen (RMF), which contains the neurovascular bundle. Accidentally damaging the neurovascular bundle in the retromolar canal during the extraction of the third molar, dental implant surgery, or maxillofacial orthognathic surgery may lead to subsequent complications such as incomplete local anesthesia, paresthesia, and bleeding during operation. The objective of this study was to investigate the prevalence of the RMF in the Taiwanese population in a medical center by using dental cone-beam computed tomography (CBCT) and to identify the position of the RMF in the mandibular bone. The dental CBCT images for the mandibular bone of 68 hemi-mandible were uploaded to the medical imaging software Mimics 15.1 to determine the prevalence of the RMF in the Taiwanese population and the three positional parameters of the RMF in the mandibular bone: (1) The diameter of the RMF, (2) the horizontal distance from the midpoint of the RMF to the distal cementoenamel junction of the second molar, and (3) the vertical distance from the midpoint of the RMF to the upper border of the mandibular canal. Seven RMFs were observed in the 68 hemi-mandibles. Thus, the RMF prevalence was 10.3%. In addition, the diameter of the RMF was 1.41 ± 0.30 mm (mean ± standard deviation), the horizontal distance from the midpoint of the RMF to the distal cementoenamel junction of the the second molar was 12.93 ± 2.87 mm, and the vertical distance from the midpoint of the RMF to the upper border of the mandibular canal below second molar was 13.62 ± 1.3487 mm. This study determined the prevalence of the RMF in the Taiwanese population in a medical center and its relative position in the mandibular bone. This information can provide clinicians with a reference for posterior mandible anesthesia and surgery to ensure medical safety.

scholarly journals Periodontal Healing Distally to Second Mandibular Molar After Third Molar Coronectomy

2017 ◽  
Vol 75 (1) ◽  
pp. 21-27 ◽  
Author(s):  
Elisabetta Vignudelli ◽  
Giuseppe Monaco ◽  
Maria Rosaria Antonella Gatto ◽  
Simonetta Franco ◽  
Claudio Marchetti ◽  
...  
Keyword(s):  
Third Molar ◽  
Mandibular Molar ◽  
Periodontal Healing

scholarly journals Influence of the Periapical Status of the Posterior Maxillary Teeth on the Width of the Schneiderian Membrane of the Maxillary Sinus Mucosa

2021 ◽  
Vol 11 (9) ◽  
pp. 3908
Author(s):  
Igor Tsesis ◽  
Eyal Rosen ◽  
Ilan Beitlitum ◽  
Einat Dicker-Levy ◽  
Shlomo Matalon
Keyword(s):  
Maxillary Sinus ◽  
Third Molar ◽  
Root Tips ◽  
Schneiderian Membrane ◽  
Second Molar ◽  
Periapical Lesions ◽  
Posterior Maxilla ◽  
Mucosal Thickness ◽  
Tooth Type ◽  
Mucosal Thickening

Background: Various parameters are known to affect the amount and type of mucosal thickening. The aim of this retrospective study was to investigate these effects through a survey of cone-beam computed tomography (CBCT) images. CBCT scans of 150 patients, which included the area of the MS and maxillary teeth (canine, first premolar, second premolar, first molar, second molar, and third molar), were evaluated retrospectively for the presence of sinus mucosal thickening. The parameters evaluated as possible causes of mucosal thickening were age, sex, tooth type, proximity to the maxillary sinus, endodontic treatment, and periapical lesion. Descriptive statistics and multiple logistic regression were used to analyze the data. A total of 28% of the teeth presented with mucosal thickening, which was associated with periapical lesions in 57.1% of 77 cases. The size of the lesion was the only parameter that was found to be significantly connected to the presence of mucosal thickness. More than 50% of teeth with periapical lesions in the posterior maxilla exhibited mucosal thickening. Other parameters such as age, sex, and the position of the root tips in relation to the MS floor did not influence the probability of developing mucosal thickening.

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