scholarly journals Effect of Genetic and Environmental Factors on the Impaction of Lower Third Molars

2021 ◽  
Vol 11 (4) ◽  
pp. 1824
Author(s):  
Giedrė Trakinienė ◽  
Dalia Smailienė ◽  
Kristina Lopatienė ◽  
Tomas Trakinis ◽  
Antanas Šidlauskas
Keyword(s):  
Environmental Factors ◽  
Environmental Effect ◽  
Third Molar ◽  
Considerable Proportion ◽  
Third Molars ◽  
Common Environment ◽  
The Third ◽  
The Common ◽  
Genetic And Environmental Factors ◽  
Third Molar Eruption

The aim of this retrospective study was to evaluate the impact of genetic and environmental factors on the impaction of lower third molars using a classical twin study by evaluation of the third molar eruption space and M3 angulation. The study group consisted of 212 twins: 80 dizygotic and 132 monozygotic twins with digital panoramic radiograms and lateral cephalograms. The zygosity of twins was determined using 15 highly polymorphic DNA regions from the venous blood of twins. The results showed that differences between siblings in the dizygotic and monozygotic twin pairs were not statistically significant. The most fitting model for the angulations of lower third molars was AE (additive genetic and specific environmental effect), where the additive genetic factors had up to 88% influence and the specific environment up to 27%. Therefore, the ACE( additive genetic, common and specific environmental effect), model showed higher significance for the lower third molar eruption level where additive genetic estimates reached 71%, a specific environment contributed up to 15% and the common environment reached 32%. The conclusion was that a considerable proportion of the third molar impaction could be attributed to additive genetic effects and the common environment, whereas the specific environment had a lower, but significant impact.

scholarly journals Third Molar Eruption Mechanisms and Patterns

2016 ◽  
Vol 4 (1) ◽  
pp. 11-16
Author(s):  
Winnie Zhang
Keyword(s):  
Molecular Mechanisms ◽  
Third Molar ◽  
Radiographic Examination ◽  
Third Molars ◽  
The Third ◽  
Occlusal Surfaces ◽  
Surgical Extraction ◽  
Incipient Caries ◽  
The Moment ◽  
Third Molar Eruption

Third molars are highly variable in their presence and form. This report focuses on a horizontally impacted third molar and analyzes the potential etiology of this situation. Upon a clinical and radiographic examination, it was noted that the patient had four third molars present. The patient’s third molars began erupting around the age of 19. Currently, they are asymptomatic with incipient caries on the occlusal surfaces. While three of the third molars erupted in a normal orientation, one of the third molars (mandibular left) erupted in an orientation that would be classified as horizontal and/or mesio-angular. No treatment has been undertaken at the moment, however surgical extraction can be recommended with the prognosis being very good. For the clinician that has to treat dental complications that arise from abnormal tooth eruption, as seen in numerous genetic and acquired disorders, knowledge about the basic molecular mechanisms involved may become extremely important.

scholarly journals Artificial Intelligence (AI)-Driven Molar Angulation Measurements to Predict Third Molar Eruption on Panoramic Radiographs

2020 ◽  
Vol 17 (10) ◽  
pp. 3716 ◽  
Author(s):  
Myrthel Vranckx ◽  
Adriaan Van Gerven ◽  
Holger Willems ◽  
Arne Vandemeulebroucke ◽  
André Ferreira Leite ◽  
...  
Keyword(s):  
Neural Network ◽  
Artificial Intelligence ◽  
Third Molar ◽  
Automated Measurement ◽  
Third Molars ◽  
Panoramic Radiographs ◽  
The Third ◽  
Clinically Significant ◽  
Reference Measurements ◽  
Third Molar Eruption

The purpose of the presented Artificial Intelligence (AI)-tool was to automatically segment the mandibular molars on panoramic radiographs and extract the molar orientations in order to predict the third molars’ eruption potential. In total, 838 panoramic radiographs were used for training (n = 588) and validation (n = 250) of the network. A fully convolutional neural network with ResNet-101 backbone jointly predicted the molar segmentation maps and an estimate of the orientation lines, which was then iteratively refined by regression on the mesial and distal sides of the segmentation contours. Accuracy was quantified as the fraction of correct angulations (with predefined error intervals) compared to human reference measurements. Performance differences between the network and reference measurements were visually assessed using Bland−Altman plots. The quantitative analysis for automatic molar segmentation resulted in mean IoUs approximating 90%. Mean Hausdorff distances were lowest for first and second molars. The network angulation measurements reached accuracies of 79.7% [−2.5°; 2.5°] and 98.1% [−5°; 5°], combined with a clinically significant reduction in user-time of >53%. In conclusion, this study validated a new and unique AI-driven tool for fast, accurate, and consistent automated measurement of molar angulations on panoramic radiographs. Complementing the dental practitioner with accurate AI-tools will facilitate and optimize dental care and synergistically lead to ever-increasing diagnostic accuracies.

scholarly journals Possibilty of the lower third molar eruption: Radiographic analysis

2006 ◽  
Vol 63 (2) ◽  
pp. 159-162
Author(s):  
Nenad Nedeljkovic ◽  
Zorana Stamenkovic ◽  
Zoran Tatic ◽  
Alek Racic
Keyword(s):  
Third Molar ◽  
Occlusal Plane ◽  
Third Molars ◽  
The Third ◽  
Crown Width ◽  
Significant Difference ◽  
Mutual Relations ◽  
The Right ◽  
B Lines ◽  
Third Molar Eruption

Backgraund/Aim. To assess the possibility of the eruption of the lower third molar on the basis of the measured parameters: retromolar space, mesiodistal crown width of a molar and the third molar angulation. Methods. The investigation included 104 patients both sexes (43 boys, and 61 girls), 16 to 25 years old (meanage, 18 years). It was performed using the orthopanthomographic radiographs analysis of those patients. Each radiograph was covered by tracing paper, and the contoures of the followiny anatomic details were drawn: a) the crown and root contours of third molars, upper and lower central incisors, distal molars in occlusion, anterior edge of ramus mandible, b) lines: 1. the occlusal plane, 2. the line of retromolar space, 3. the mesiodistal crown width of third molar, 4. the axial shaft of the third molar and the distal angle between occlusal plane and the axial shaft of the third molar. The values were measured with an orthodontic caliper: the diameter of retromolar space, diameter of mesiodistal width, the value of distal angle between occlusal plane and axial shaft of molar. Results. A favourable angulation of the lower third molar (more than 60?) was found in, boys (left 27.90%, right 32.55%), girls (left 39.34%, right 37.77%). A favourable relationship between the diameters of mesiodistal width of the third molar and retromolar space was found in, boys, (left 13.59%, right 16.27%), girls, (left 8.19%, right 14.75%). A favorable relationship between the diameters of mesiodistal width of the third molar and the retromolar space and the angulation was found in boys, (left 9.30%, right 11.62%), girls, (left 6.56%, right 9.83%). Conclusion. There was not any statistically significant difference found between the relation of the retromolar value, third molar mesiodistal diameter, or of the third molar angulation to the left and the right side nor of their mutual relations in comparing boys and girls. A favorable prognosis was found in 9.33% of the patients.

scholarly journals Size of the lower third molar space in relation to age in Serbian population

2013 ◽  
Vol 70 (10) ◽  
pp. 923-928 ◽  
Author(s):  
Ksenija Zelic ◽  
Nenad Nedeljkovic
Keyword(s):  
Age Groups ◽  
Third Molar ◽  
Adult Patients ◽  
Width Ratio ◽  
Third Molars ◽  
Gonial Angle ◽  
Angle Size ◽  
The Third ◽  
Crown Width ◽  
Third Molar Eruption

Background/Aim. It is considered that the shortage of space is the major cause of the third molar impaction. The aim of this study was to establish the frequency of insufficient lower third molar eruption space in Serbian population, to question the differences in this frequency in the subjects of different age, to determine the influence of the lower third molar space (retromolar space) size on third molar eruption, and to investigate a possible correlation between the size of gonial angle and the space/third molar width ratio. Methods. Digital orthopantomograms were taken from 93 patients divided into two groups: early adult (16-18 years of age) and adult (18-26) patients. Retromolar space, mesiodistal third molar crown width, gonial angle and eruption levels were measured. Results. The space/third molar width in early adult subjects was smaller (p < 0.0001) and insufficient space was significantly more frequent (p = 0.0003) than in adult patients. Considerably more third molars erupted in case of enough space in both age groups (p < 0.0001). There was no difference between the means of gonial angle size in relations to the available space. Conclusions. The retromolar space/third molar width ratio is more favorable in adult subjects. Gonial angle is not in correlation with the retromolar space/third molar width ratio.

scholarly journals Evaluation of Panoramic Radiographs in Relation to the Mandibular Third Molar and to Incidental Findings in an Adult Population

2020 ◽  
Author(s):  
Josefine Cederhag ◽  
Nina Lundegren ◽  
Per Alstergren ◽  
Xie-Qi Shi ◽  
Kristina Hellén-Halme
Keyword(s):  
Incidental Findings ◽  
Adult Population ◽  
Inferior Alveolar Nerve ◽  
Third Molar ◽  
Patient Positioning ◽  
Vertical Position ◽  
Surgical Removal ◽  
Third Molars ◽  
Panoramic Radiographs ◽  
The Third

Abstract Objectives The aim was to evaluate the characteristics of the mandibular third molars, especially in relation to the inferior alveolar nerve. Further aims were to investigate incidental findings in panoramic radiographs in an adult population, and to investigate image quality related to patient positioning. Materials and Methods From a previous study with 451 randomly selected adult participants who lived in Sweden, 442 panoramic radiographs from four dental public health clinics were used. The third molars’ characteristics and relation to inferior alveolar nerve were evaluated. Incidental findings and patient positioning were recorded. Statistical Analysis Frequency analysis was used to investigate the occurrence of all findings and their possible interconnections. Whether the patients’ age or gender had an impact or not was also analyzed. Results The third molars were erupted in vertical position among 73% regardless of age. When retained or semi-retained, they were most commonly in mesioangular positions. The inferior alveolar nerve was located inferior to the roots in 52%, whereas an overlapped position was most common if the third molar was retained (90%), semi-retained (83%) or the age was less than 30 years (66%). Common incidental findings were apical radiolucencies, idiopathic osteosclerosis, and tooth fragments. Suboptimal patient positioning was found in one-third of the radiographs. Conclusions Panoramic radiography is a useful method to evaluate third molar prior to surgical removal and may be the only image required. Most incidental findings on panoramic radiographs does not seem to require any further odontological management.

scholarly journals Evaluation of Hemodynamic Cerebral Disordersin Patients Subjected to the Third Molar Extraction.Evaluation of the Effectiveness of OsteopathicRehabilitation after Tooth Extraction

2016 ◽  
pp. 60-66
Author(s):  
А. . Atyakshev ◽  
N. . Tekoutieva
Keyword(s):  
Tooth Extraction ◽  
Third Molar ◽  
Cerebral Hemodynamics ◽  
Third Molars ◽  
The Third ◽  
Upper Jaw ◽  
Rehabilitation Measures

Extraction of the third molars from the upper jaw can cause somatic dysfunctions and changes in cerebral hemodynamics in patients. Rehabilitation measures aimed to correct somatic dysfunctions and restore cerebral hemodynamics are necessary for these patients.

scholarly journals The Frequency of Mandibular Third Molar Impaction in Different Types of Vertical Skeletal Faces

2021 ◽  
Vol 30 (02) ◽  
pp. 118-123
Author(s):  
Sana Viqar ◽  
◽  
Sadia Rizwan ◽  
Syed Shah Faisal ◽  
Syed Sheeraz Hussain
Keyword(s):  
Third Molar ◽  
Third Molars ◽  
Skeletal Malocclusion ◽  
Mandibular Third Molar ◽  
Lateral Cephalograms ◽  
Significant Difference ◽  
Pre Treatment ◽  
Mandibular Third Molars ◽  
Facial Types ◽  
Third Molar Eruption

OBJECTIVE: To determine the frequency of mandibular third molar impaction in different vertical skeletal facial types. METHODOLOGY: Data was collected using pre-treatment records including orthodontic files, pre-treatment lateral cephalograms and OPGs of 90 orthodontic patients. Patients from both genders were included. The age group of selected patients was 18-30 years. Vertical skeletal malocclusion was measured using facial angle and mandibular plane angle on cephalogram to group the subjects into Mesiofacial, Brachyfacial and Dolichofacial patients. Third molar eruption status was assessed using OPG. RESULTS: Results showed that erupted third molars were mostly found in brachyfacial patients. Among 32 erupted mandibular third molars, 16 belong to brachyfacial, 11 belonged to mesiofacial and 5 belonged to dolichofacial group. Complete impaction of mandibular third molar was most common among dolichofacial patients. Among 29 completely impacted mandibular third molars, 14 belong to dolichofacial, 9 belonged to mesiofacial and 6 belonged to brachyfacial group. No significant difference was found for partially impacted third molars among the three groups of facial types. There was higher prevalence of mandibular third molar impaction in females as compared to males. CONCLUSION: Frequency of third molar impaction was found to be highest in dolichofacial patients and lowest in brachyfacial patients due to forward direction of mandibular growth contributing to greater resorption of the anterior border of ramus and the additional space required for third molar eruption.

scholarly journals Accuracy of cone-beam computed tomography in defining spatial relationships between third molar roots and inferior alveolar nerve

2016 ◽  
Vol 10 (04) ◽  
pp. 454-458 ◽  
Author(s):  
Roberto Pippi ◽  
Marcello Santoro ◽  
Ferdinando D'Ambrosio
Keyword(s):  
Computed Tomography ◽  
Cone Beam Computed Tomography ◽  
Root Morphology ◽  
Inferior Alveolar Nerve ◽  
Third Molar ◽  
Root Surface ◽  
Cone Beam ◽  
Spatial Relationships ◽  
Third Molars ◽  
The Third

ABSTRACT Objective: Cone-beam computed tomography (CBCT) has been proposed in surgical planning of lower third molar extraction. The aim of the present study was to assess the reliability of CBCT in defining third molar root morphology and its spatial relationships with the inferior alveolar nerve (IAN). Materials and Methods: Intraoperative and radiographic variables of 74 lower third molars were retrospectively analyzed. Intraoperative variables included IAN exposure, number of roots, root morphology of extracted third molars, and presence/absence of IAN impression on the root surface. Radiographic variables included presence/absence of the cortex separating IAN from the third molar roots on CBCT examination, number of roots and root morphology on both orthopantomography (OPG) and CBCT. The statistical association between variables was evaluated using the Fisher's exact test. Results: In all cases of intraoperative IAN exposure, the cortex appeared discontinuous on CBCT images. All cases, in which the cortical bone was continuous on CBCT images, showed no association with nerve exposure. In all cases in which nerve impression was identified on the root surface, the IAN cortex showed interruptions on CBCT images. No nerve impression was identified in any of the cases, in which the cortex appeared continuous on CBCT images. CBCT also highlighted accessory roots and apical anomalies/curvatures, not visible on the OPG. Conclusions: CBCT seems to provide reliable and accurate information about the third molar root morphology and its relationship with the IAN.

The Oblique Lateral Jaw Radiograph

1974 ◽  
Vol 1 (4) ◽  
pp. 139-142
Author(s):  
C. P. Adams
Keyword(s):  
Present Article ◽  
Third Molar ◽  
Third Molars ◽  
X Ray ◽  
The Third ◽  
Molar Teeth ◽  
Relationship Of ◽  
The Relationship ◽  
Film Area

The Oblique Lateral Jaw Radiograph has been used as a routine diagnostic x-ray view for many years as an aid to orthodontic diagnosis and for the assessment of the positions of unerupted third molar teeth. Many methods for obtaining clear undistorted views of the teeth have been suggested from a freehand setting up of film, patient and x-ray tube, to the use of simple orientated devices. The present article describes a method of standardizing the relationship of film and x-ray tube to one another so that it is only necessary for the radiographer thereafter to place the patient on the film area in a manner depending on whether a view. is required of the third molars only or of the complete upper and lower buccal segments.

Genes, environments and depressions in young people

2015 ◽  
Vol 100 (11) ◽  
pp. 1064-1069 ◽  
Author(s):  
Ian M Goodyer
Keyword(s):  
Young People ◽  
Environmental Factors ◽  
Mental Illnesses ◽  
Childhood And Adolescence ◽  
The Common ◽  
Genetic And Environmental Factors

Among the common mental illnesses in childhood and adolescence, the unipolar depressions are the most concerning. These mental illnesses are aetiologically and clinically heterogeneous and little is known about their pathophysiology. This selected review considers the contribution of genetic and environmental factors in the emergence of these illnesses in the second decade of life.

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