A longitudinal study on timing and velocity of rat molar eruption: Timing of rat molar eruption

Rat molar eruption and occlusion data were compiled from several studies but several inconsistencies were found, rendering the planning of eruptional studies difficult and imprecise. Our aim was to measure eruption and occlusion days, as well as eruption velocity, in the upper and lower three molars from infancy to end of adolescence in the rat. A total of 19 male and female Wistar rats were scanned daily by micro-computed tomography (CT) from day 15 to 70. We measured the eruption of all maxillary and mandibular molars with reference points at the hard palate and mandibular canal at three stages: pre-emergent, pre-occlusal, and functional. Statistical analysis was performed with a mixed-model analysis of variance (ANOVA) and a Sidak post hoc test. The first molar erupts on average on day 17, the second molar on day 20, and the third molar on day 33. The eruption velocity of the first molar was the highest at 90.9 microns/day (standard error (se) = 12.80), followed by the second molar at 65.9 microns/day (se = 5.80), and the lowest was the third at 47.0 microns/day (se = 3.28), ( p < 0.001). On average, the pre-occlusal phase had the highest velocity at 97.2 microns/day (se = 1.72), the pre-emergent was lower at 84.9 (se = 2.29), and the functional was the lowest at 21.7 (se = 0.45), ( p < 0.001). The eruption rate decreased from the first to third molar and was also different between phases: the pre-occlusal phase had the highest rate, closely followed by the pre-emergent phase while the functional eruption rate was significantly lower than the other phases.

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

Tomography ◽

10.3390/tomography7020020 ◽

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.

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Evaluation of Mandibular Third Molar Region in a Turkish Population Using Cone-Beam Computed Tomography

Current Medical Imaging Formerly Current Medical Imaging Reviews ◽

10.2174/1573405616666200103094611 ◽

2020 ◽

Vol 16 (9) ◽

pp. 1105-1110

Author(s):

Büyük Kaan Orhan ◽

Dilek Yılmaz ◽

Mehmet Ozgur Ozemre ◽

Kıvanç Kamburoğlu ◽

Orhan Gulen ◽

...

Keyword(s):

Statistical Significance ◽

Third Molar ◽

Mandibular Canal ◽

Third Molars ◽

Second Molar ◽

The Third ◽

Impacted Mandibular Third Molar ◽

Mandibular Third Molar ◽

The Relationship ◽

Molar Region

Objectives: To evaluate impacted mandibular third molar tooth region and obtain linear measurements using CBCT images and to assess the relationship between the impacted third molar and the mandibular canal. Methods: CBCT scans of 351 patients (208 females, 143 males) were assessed. Age, gender, and impaction site were recorded for each patient. The relationship of third molars with the vertical axis of second molars, 2nd molar resorption and the relationship between third molar apices and the mandibular canal were assessed. In addition, the distance between ramus and second molar, mesiodistal width of the third molar, the angle between third molar and second molar, and width of the third molar capsule were measured. Binary Logistic Regression, Chi-Square Test, and General Linear Model were used for statistical analysis. Results: The highest percentage of impaction was found for mesioangular followed by transversal and vertical. The transversal impacted third molars revealed a significant association with adjacent second molar root resorption (p<0.001). There was a statistical significance between the second molar resorption and distance between ramus and second molar (p<0.001). The mesioangular impacted third molars revealed significant relation with the mandibular canal (p<0.05). The most frequent variation found was the dental canal followed by the retromolar canal. In general, higher measurement values were obtained for men when compared to women (p<0.05). Conclusion: CBCT assessment of the third molar region provided useful information regarding impacted mandibular third molar surgery operations.

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Panoramic Radiographic Analysis of Signs of Proximity to the Third Molar Roots of the Mandibular Canal in Yemen

Journal of Medical Clinical Case Reports ◽

10.47485/2767-5416.1017 ◽

2020 ◽

Keyword(s):

Third Molar ◽

Mandibular Canal ◽

Cross Sectional Study ◽

Third Molars ◽

Cross Sectional ◽

Panoramic Radiographs ◽

Second Molar ◽

Female Patients ◽

The Third ◽

Dental Clinics

Objectives: The objectives of this study were to assess the relationship between the third molar and the mandibular canal, to identify the radiographic markers most prevalent in predicting connectivity between these structures, and to associate these signs and proximity with the position of the third molar according to Bell, Gregory’s and Winter’s classifications. Subjects and methods: A retrospective cross-sectional study was conducted in the city of Sana’a on a sample of Yemeni patients in Ammar Dental Clinics who underwent panoramic radiography in the year 2019 until September 2020. The study consisted of panoramic radiographs of 597 patients with third molars with a total of 1017 third molars; the number of males was 216 (36.2%) and 381 females (63.8%). The panoramic radiographs were evaluated for proximity signs. Inclusion criteria were patients of both sexes who had at least a fully formed third molar of the mandible that was adjacent to the second molar. The radiographs were excluded if evidence of cystic, neoplastic, or extensive caries processes was detected. Seven radiological signs were used to determine if there was contact between the third molar and the mandibular canal. Results: A proximity to the mandibular canal was verified for 620 (61%) of 1017 third molars. The most frequent radiographic signs of proximity were darkened roots (315 teeth [31%]) and discontinuity of the mandibular canal (267 teeth [26.3%]). Third molar/mandibular canal proximity was found significantly more frequently in female patients and in patients aged 24 years and younger (P < 0.001). The tooth positions most frequently associated with proximity between the third molar and the mandibular canal were position C (highest point of the third molar located at or below the cervical margin of the second molar) and the mesioangular position (long axis of the third molar angled mesially toward the second molar). Conclusions: The frequency of third molar/ mandibular canal proximity was greater in female patients and patients aged 24 years or younger. The most frequently observed signs of proximity were darkening of the roots and discontinuity of the mandibular canal. The tooth positions most frequently associated with proximity of the third molar to the mandibular canal were position C and the mesioangular position.

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The Anatomical Position and Size of Greater Palatine Foramen and Canal in an Iranian Sample Using Cone Beam Computed Tomography

10.21203/rs.3.rs-800991/v1 ◽

2021 ◽

Author(s):

Solmaz Valizadeh ◽

Seyedeh Mahshid Ahmadi ◽

Mitra Ghazizadeh Ahsaie ◽

Zahra Vasegh ◽

Navid Jamalzadeh

Keyword(s):

Computed Tomography ◽

Average Length ◽

Third Molar ◽

Cone Beam ◽

P Value ◽

Second Molar ◽

Anatomical Position ◽

The Third ◽

Greater Palatine Foramen ◽

The Right

Abstract IntroductionDetection of exact location of greater palatine foramen and its anatomical variations are vital prior to posterior maxillary surgeries and gingival grafts. The aim of this study is to determine the anatomical position and size of the greater palatine canal (GPC) and foramen (GPF) using cone beam computed tomography (CBCT) scans.Materials and methodsIn this descriptive-analytic study, CBCT images of 148 patients were assessed. To determine the anatomical foramen position, the posterior maxilla area was divided into five regions on the axial view (A: from the mesial surface of the second molar to the center of the second molar, B: from the center of the second molar to its distal, C: from the mesial surface of the third molar to the center of the third molar, D: from the center of the third molar to the distal of the third molar, E: distal to the third molar.). The length of the canal was investigated on both coronal and sagittal views. Independent and paired T-test were used to analyze the data.ResultsAmong 80 females -68 males, the anatomical position of the GPF was mainly located in region E on the left (55%) and the right (50%), and then, respectively, in region D and region C. The mean diameter of GPF was 4/48 mm on the left and 4/63 mm on the right side (P-value = 0/01). The average length of the canal on the coronal view was 29.46 mm on the left side and 29.75 mm on the right (P-Value = 0/005). The average length of the canal on the sagittal view was 29.62 mm on the left and 30.02 mm on the right (P-value = 0/001).ConclusionThe anatomical position of the GPF was primarily located distal to the third maxillary molar. CBCT is a valuable diagnostic tool for evaluation of vital anatomic landmarks in the maxillofacial region prior to surgeries and interventions.

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Association between imaging and clinical findings in mandibular third molar surgeries

Revista da Faculdade de Odontologia - UPF ◽

10.5335/rfo.v23i1.8127 ◽

2018 ◽

Vol 23 (1) ◽

Author(s):

Marcelo Bonifácio da Silva Sampieri ◽

Danilo Da Silva Correa ◽

Francisca Lívia Parente Viana ◽

Thaís Sumie Nozu Imada ◽

Josfran Da Silva Ferreira Filho ◽

...

Keyword(s):

Computed Tomography ◽

Cone Beam Computed Tomography ◽

Statistical Significance ◽

Third Molar ◽

Panoramic Radiograph ◽

Mandibular Canal ◽

Clinical Findings ◽

Cone Beam ◽

The Third ◽

Close Relationship

Objective: it is important to evaluate the position andestablish the third molar relationship with the mandibularcanal to minimize the risk of nerve injury and assistin planning the extraction of this tooth. The panoramicradiograph is the standard diagnostic tool for this purpose.However, if it indicates a close relationship betweenthe third molar and the mandibular canal, furtherinvestigation using cone beam computed tomography(CBCT) may be recommended to check the three-dimensionalrelationship between the tooth and the mandibularcanal. Thus, this study aimed to correlate the clinicalfindings (observed in third molar surgeries) to imagingfindings (observed in panoramic radiographs andCBCT). Subjects and method: after the extraction of 20mandibular third molars, the panoramic radiograph andthe cone beam computed tomography were analyzed.Then, the surgical findings were correlated to the imagefindings. Results: It was observed that the radiographicfinding type 2 (darkening of roots) observed in the panoramicradiograph presented a greater relation to theabsence of cortical bone between the mandibular canaland the third molar (CBCT finding), with statistical significance(p

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Prevention of Periodontal Pocket Formation after Mandibular Third Molar Extraction Using Dentin Autologous Graft: A Split Mouth Case Report

Case Reports in Dentistry ◽

10.1155/2020/1762862 ◽

2020 ◽

Vol 2020 ◽

pp. 1-7 ◽

Cited By ~ 1

Author(s):

Alberto De Biase ◽

Giulia Mazzucchi ◽

Dario Di Nardo ◽

Marco Lollobrigida ◽

Giorgio Serafini ◽

...

Keyword(s):

Case Report ◽

Third Molar ◽

Periodontal Pocket ◽

Pocket Depth ◽

Second Molar ◽

The Third ◽

Third Molar Extraction ◽

Probing Pocket Depth ◽

Surgical Extraction ◽

A Minor

Surgical extraction of the third molar can often result in the development of a periodontal pocket distal to the second molar that could delay the healing, and the socket could be colonized by bacteria and lead to secondary abscesses, or it may cause mobility or hypersensitivity. The aim of this case report is to assess the efficacy of a dentin autograft in the prevention of periodontal dehiscences after the surgical extraction of the third molar, obtained by the immediate grinding of the extracted tooth. A healthy 18-year-old male patient underwent surgery of both impacted mandibular molars: right postextractive socket was filled with grinded dentin; then, the left one was filled with fibrin sponge. The patient was followed up for six months, and clinical and radiographic assessment were performed: measurements of plaque index (PI), bleeding on probing (BOP), gingival index (GI), clinical attachment level (CAL), and probing pocket depth (PPD) were done before surgery and repeated at 90 and 180 days after the extractions. Measurements made at six months after the surgery revealed that the grafted site was characterized by a minor depth of the pocket if compared with the nongrafted site, with no clinical/radiographic signs of complications.

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The Criteria for Lower Second Molar Extraction

British Journal of Orthodontics ◽

10.1179/bjo.14.1.1 ◽

1987 ◽

Vol 14 (1) ◽

pp. 1-9 ◽

Cited By ~ 12

Author(s):

J. T. Dacre

Keyword(s):

Selection Criteria ◽

Third Molar ◽

Second Molar ◽

The Third ◽

The Right ◽

Molar Extraction

The benefits of lower second molar extraction are substantially reduced if the third molar fails to erupt into a satisfactory position. The selection criteria offered by the literature have been tested in a sample of 51 patients. Prediction is uncertain and cases should be followed until such time as a satisfactory third molar position has been achieved. Failure may be unilateral and more often on the right side. The need for follow-up treatment is subjective but may be as many as one in the patients.

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Is the Jaw Bone Micro-Structure Altered in Response to Osteoporosis and Bisphosphonate Treatment? A Micro-CT Analysis

International Journal of Molecular Sciences ◽

10.3390/ijms22126559 ◽

2021 ◽

Vol 22 (12) ◽

pp. 6559

Author(s):

Marissa Chatterjee ◽

Fernanda Faot ◽

Cassia Correa ◽

Jente Kerckhofs ◽

Katleen Vandamme

Keyword(s):

Negative Impact ◽

Ex Vivo ◽

Third Molar ◽

Pairwise Comparison ◽

Preventive Treatment ◽

Regions Of Interest ◽

Bisphosphonate Treatment ◽

Micro Computed Tomography ◽

Jaw Bone ◽

Second Molar

The aim of the study was to quantify the micro-architectural changes of the jaw bone in response to ovariectomy, exposed or not to bisphosphonate treatment. A total of 47 Wistar rats were ovariectomized (OVX) or sham-operated (shOVX) and exposed to osteoporosis preventive treatment for eight weeks either with bisphosphonates (alendronate, ALN; group OVX-ALN) three days/week at a dose of 2 mg/kg or with saline solution (untreated control condition; group OVX). The bone morphometric parameters of the trabecular jaw bone were assessed using ex vivo micro-computed tomography. The regions of interest investigated in the maxilla were the inter-radicular septum of the second molar and the tuber. The regions quantified in the mandible included the three molar regions and the condyle. A one-way analysis of variance followed by pairwise comparison using Tukey’s HSD and the Games–Howell test was conducted to explore significant differences between the groups. In the maxilla, OVX decreased the bone volume in the inter-radicular septum of the second molar. Bisphosphonate treatment was able to prevent this deterioration of the jaw bone. The other investigated maxillary regions were not affected by (un)treated ovariectomy. In the mandible, OVX had a significant negative impact on the jaw bone in the buccal region of the first molar and the inter-radicular region of the third molar. Treatment with ALN was able to prevent this jaw bone loss. At the condyle site, OVX significantly deteriorated the trabecular connectivity and shape, whereas preventive bisphosphonate treatment showed a positive effect on this trabecular bone region. No significant results between the groups were observed for the remaining regions of interest. In summary, our results showed that the effects of ovariectomy-induced osteoporosis are manifested at selected jaw bone regions and that bisphosphonate treatment is capable to prevent these oral bone changes.

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Kajiansudut inklinasi gigi molar ketiga rahangbawahpre-erupsi pada kelompok umur14 -17 tahun(The pre-eruptedstudyof mandibular thirdmolar inclinationamong 14 to 17 year old)

Journal of Dentomaxillofacial Science ◽

10.15562/jdmfs.v13i2.396 ◽

2014 ◽

Vol 13 (2) ◽

pp. 95

Author(s):

Nurlailia DS ◽

Mei Syafriadi

Keyword(s):

Third Molar ◽

Population Group ◽

Age Group ◽

Second Molar ◽

Group Iii ◽

The Third ◽

Tooth Impaction ◽

Molar Teeth ◽

To Come ◽

Ray Projection

At the beginning of the growth, tooth inclination is mesioangular, then move gradually to come into contact with thedistal surface of the second molar and further commit to sliding movement parallel to second molar axis. This positionwill be retained to achieve the eruption way to oral cavity. However, the last decade reported incidence increasedimpaction of the third molar teeth in the lower jaw. This study was aimed to study the level of pre-eruption of mandibularthird molar in the population group aged 14-17 years to predict the risk of tooth impaction or not. Differentiatedpopulations on cluster I, age 14-15 years old; group II, 15.1-16 years old; and group III 16.1-17 years old. Researchcarried out by clinical observation and measurement of at Department of Radiology in Jember University with 48people selected based on predetermined criteria. X-ray projection was exposed by paralleling technique on the lowerthird molar teeth, left and right. The results showed 43.75% of 14-15 year old group had the third molar angle interval50-56°; 15.1-16 year age group, 80% have 57-70° angle interval, and 16.1-17 years age group, 46.67% has angularinterval 64-70°. It was concluded that a large interval of the third molar angle increase due to the increased of age,and the angle is different between groups based on gender.

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Molar space closure: To do or not to do?

APOS Trends in Orthodontics ◽

10.25259/apos_112_2021 ◽

2021 ◽

Vol 0 ◽

pp. 1-8

Author(s):

Nutthakarn Ratanasereeprasert ◽

Chu-Yin Weng ◽

Stella Ya-Hui Yang ◽

Yi-Jane Chen ◽

Chung-Chen Jane Yao

Keyword(s):

Treatment Planning ◽

Treatment Plan ◽

Treatment Options ◽

Third Molar ◽

Case Series ◽

Space Management ◽

Second Molar ◽

The Third ◽

Space Closure ◽

Permanent Molars

Missing or compromised permanent molars can complicate orthodontic treatment planning and mechanics. Molar extraction should be considered in appropriate situations, but clinicians must decide between closing and regaining the edentulous space. Several factors should be taken into consideration to achieve appropriate molar space management, such as the need for space, asymmetry, periodontal status, sinus pneumatization, and the terminal molar position. Herein, three sample cases are reported to demonstrate the treatment options for molar space closure and maintenance with these factors taken into consideration during treatment planning. The understanding of mechanics played a crucial role in anchorage preparation and side effect prevention. If the third molar substitution was managed in advance and adequate space between the ramus and third molar was obtained via second molar protraction, the tooth spontaneously erupted in a favorable position without requiring further treatment. This case series can aid clinicians in molar space management. Regardless of whether the space is to be closed or regained, the treatment plan should conform to the patient’s expectations and improve occlusion with minimal side effects and treatment duration.

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