New Classification for Bifurcated Mandibular Neural Canal

Abstract Background: To analyze the occurrence rate of bifurcated neural canal (BMC) by cone beam CT(CBCT) and summarise a new classification for further clinical work and academic communication. Method: Randomly collected the CBCT images of 350 patients. Firstly, we analysed and summarized the BMCs into four types. Second, we did statistics about occurrence. Then we have measured three kinds of distance of Type I and Type II. At last, we compared the advantages and disadvantages about different classifications. Results: Among these 350 patients, we found 110 people with BMC which indicated the occurrence rate of BMC was 31.43%. The most common type was Type I, especially Type I B , and the least was Type III. Vertical distance between the apex of the second molar, the third molar and mandibular canal are 4.36±2.51 mm and 2.45±2.23 mm. Distance from the apex of two molars to the bifurcated spot are 15.87±6.82mm and 9.32±5.37mm. And the distance between the apex and retromolar foramen in Type I are 22.19±5.97mm and 15.82±4.68mm. Conclusion: Comparing with former typing theory, we summarized a new classification which is simpler and more convenient, which should attach scholars’ attention to BMC during clinical work.

Download Full-text

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.

Download Full-text

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

Laboratory Animals ◽

10.1177/0023677217750410 ◽

2018 ◽

Vol 52 (4) ◽

pp. 394-401 ◽

Cited By ~ 3

Author(s):

Balazs J Denes ◽

Aikaterini Lagou ◽

Domna Dorotheou ◽

Stavros Kiliaridis

Keyword(s):

Mixed Model ◽

Third Molar ◽

Mandibular Canal ◽

Reference Points ◽

Micro Computed Tomography ◽

Eruption Rate ◽

Second Molar ◽

Mixed Model Analysis ◽

The Third ◽

Rat Molar

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.

Download Full-text

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.

Download Full-text

Case Report: Ectopic third molar in the maxillary sinus with infected dentigerous cyst assessed by cone beam CT

F1000Research ◽

10.12688/f1000research.22466.2 ◽

2020 ◽

Vol 9 ◽

pp. 209

Author(s):

Khairy Elmorsy ◽

Lubna K. Elsayed ◽

Sara M. El Khateeb

Keyword(s):

Maxillary Sinus ◽

Cone Beam Ct ◽

Dentigerous Cyst ◽

Third Molar ◽

Panoramic Radiograph ◽

Cone Beam ◽

Purulent Discharge ◽

Uneventful Recovery ◽

Radiographic Examination ◽

Second Molar

Ectopic development of teeth in nondental areas is uncommon, especially in the maxillary sinus. A panoramic radiograph is the routine diagnostic radiographic examination performed for this type of eruption, although cone beam computed tomography (CBCT) is highly recommended for further localization of the ectopic tooth and assessment of the characteristics of any associated lesion before a surgical procedure. We report a case of a 13-year-old female student who presented with purulent discharge posterior to the upper right second molar with a bad taste and foul odour. Radiographic examination revealed a maxillary third molar tooth located at the posterosuperior aspect of the right maxillary sinus with a hyperdense lesion surrounding the crown, obliterating the sinus cavity. Both the tooth and dentigerous cyst were surgically removed under general anaesthesia through Caldwell-Luc antrostomy. After a three-month follow-up, the patient was symptom free and had an uneventful recovery. The rare and critical location of the reported third molar along with the infected dentigerous cyst indicates its complete enucleation to avoid complications as recurrence or malignant transformation.

Download Full-text

Comparison of CBCT and panoramic radiography for the assessment of bone loss and root resorption on the second molar associated with third molar impaction: a systematic review

Dentomaxillofacial Radiology ◽

10.1259/dmfr.20210217 ◽

2021 ◽

pp. 20210217

Author(s):

Larissa Moreira-Souza ◽

Luciana Butini Oliveira ◽

Hugo Gaêta-Araujo ◽

Marcia Almeida-Marques ◽

Luciana Asprino ◽

...

Keyword(s):

Bone Loss ◽

Root Resorption ◽

Panoramic Radiography ◽

Cone Beam Ct ◽

Third Molar ◽

Risk Of Bias ◽

Marginal Bone Loss ◽

Second Molar ◽

Impacted Third Molar ◽

External Root Resorption

Objective: To investigate whether the use of cone beam CT (CBCT) changes the diagnosis of external root resorption (ERR) or marginal bone loss (MBL) involving a second molar adjacent to an impacted third molar. Methods: A systematic search was applied in PubMed, EMBASE, Scopus, Web of Science, LILACS, Google Scholar, OpenGrey, and ProQuest. Studies assessing the detection of ERR or MBL in a second molar adjacent to an impacted third molar through CBCT and panoramic radiography (PAN) were included. Prevalence and agreement between PAN and CBCT on the detection of ERR and MBL were collected. The risk of bias was assessed using the MAStARI. Results: A total of 593 papers were identified, and after a 2-phase selection, 5 studies were included in the narrative synthesis. Regarding ERR, its prevalence in PAN was reported from 5.31 to 19.5% and from 22.8 to 62.0% in CBCT. The percentage of agreement varied from 28.5 to 74.0%. The prevalence of MBL varied from 21.9 to 62.9% in PAN, while those values varied from 21.6 to 80% in CBCT images. The percentage of agreement between PAN and CBCT for the detection of MBL ranged from 66.0 to 85.0%. Four studies presented low risk of bias and one had moderate risk. Conclusions: More ERR and MBL are assessed in CBCT compared to PAN. There is a considerable agreement between PAN and CBCT assessment of ERR and MBL, however, mostly related to the absence of the pathology rather its presence.

Download Full-text

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.

Download Full-text

Case Report: Ectopic third molar in the maxillary sinus with infected dentigerous cyst assessed by cone beam CT

F1000Research ◽

10.12688/f1000research.22466.1 ◽

2020 ◽

Vol 9 ◽

pp. 209

Author(s):

Khairy Elmorsy ◽

Lubna K. Elsayed ◽

Sara M. El Khateeb

Keyword(s):

Maxillary Sinus ◽

Cone Beam Ct ◽

Dentigerous Cyst ◽

Third Molar ◽

Panoramic Radiograph ◽

Cone Beam ◽

Purulent Discharge ◽

Uneventful Recovery ◽

Radiographic Examination ◽

Second Molar

Download Full-text

Radiographic assessment of mandibular canal in Nepalese population: a study based on cone beam computed tomography images

Journal of Chitwan Medical College ◽

10.3126/jcmc.v9i4.26902 ◽

2019 ◽

Vol 9 (4) ◽

pp. 52-56

Author(s):

Pragya Shrestha ◽

Dil Islam Mansur ◽

Manoj Humagain ◽

Sushmit Koju ◽

Sunima Maskey

Keyword(s):

Inferior Alveolar Nerve ◽

Third Molar ◽

Mandibular Canal ◽

The Body ◽

Cone Beam ◽

Cortical Plate ◽

Second Molar ◽

Computed Tomography Images ◽

Adjacent Structures ◽

Relationship Of

Background: Mandibular canal runs in the body and ramus of mandible and provides passage for inferior alveolar nerve. Knowledge on spatial relationship of canal with adjacent structures prevent damage to nerve during surgical procedures. This study aims to find three-dimensional relationship of canal as well as its relation with third molar. Methods: This was a cross sectional and retrospective study conducted on Cone Beam Computed Tomography images. The relation and position of canal with third molar and position of canal in vertical and horizontal dimensions were analyzed. Results: Mandibular canal was found to be progressively descended in 43% of the canals. The canal was located apical to third molar in 61.9% cases and regarding contact relation, 121(56%) of the third molars had no contact with the canal. Buccal cortical plate was maximum at the level of distal root of second molar and minimum at the level of mesial root of first molar and was reverse for lingual cortical plate. The highest distance between upper border of canal and inferior border of mandible was at mental foramen 13.55±2.27 mm and lowest at mesial root of second molar, 8.72±2.59 mm. Minimum distance between superior border of canal and alveolar crest was distal to second molar (13.78±3.54 mm) and maximum between first molar and second premolar (17.91±3.08 mm). Conclusions: It was observed that canal was interradicularly placed and was by penetrated by third molar in some cases. Thickness of cortical plates varied in various locations buccally and lingually.

Download Full-text

Minimum size and positioning of imaging field for CBCT-scans of impacted lower third molars: a retrospective study

BMC Oral Health ◽

10.1186/s12903-021-02029-6 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Anne-Mari Ilo ◽

Marja Ekholm ◽

Elmira Pakbaznejad Esmaeili ◽

Janna Waltimo-Sirén

Keyword(s):

Retrospective Study ◽

Three Dimensional ◽

Third Molar ◽

Mandibular Canal ◽

Minimum Size ◽

Computer Assisted ◽

Third Molars ◽

Second Molar ◽

Medial Side ◽

Three Dimensional Coordinate

Abstract Background Cone-beam Computed Tomography (CBCT) is widely used for preoperative 3D imaging of lower third molars. Hence, for this imaging indication, the present study aimed to define the minimum field-of-view (FOV) size and its optimum placement, to decrease radiation exposure, and highlight the need of computer-assisted FOV centering technique for dental CBCT devices. To facilitate proper placement of image field, lower second molar was chosen as reference. Methods The retrospective study included 50 CBCT-scans of 46 patients with mean age of 34 years. Based on the lower second molar, a three-dimensional coordinate was formed and the location of mandibular canal (MC) and the dimensions and locations of the lower third molars, and possible associated pathological findings were assessed. Accordingly, the FOV size and position for third-molar imaging were optimized, while ensuring encompassment of all relevant structures. Results The minimum cylindrical volume, covering lower third molars and MC, was 32.1 (diameter) × 31.6 (height) mm, placed in relation to the second molar crown, top 2.2 mm above cusp tips, anterior edge 6.7 mm in the front of the most distal point of the crown, and lingual edge 7.9 mm on the medial side of the lingual wall. Conclusions The optimized FOV for lower third molars was smaller than common standard small FOVs. We recommend using FOV volume 3.5∅ × 3.5 cm for third molars without associated pathology. Accurate FOV protocols are essential for development of new CBCT-devices with computer-assisted and indication-specific FOV placement.

Download Full-text

DIFFERENTIATED APPROACH TO THE SURGICAL EXTRACTION OF WISDOM TEETH

Ukrainian Dental Almanac ◽

10.31718/2409-0255.4.2019.04 ◽

2019 ◽

pp. 24-28

Author(s):

A.I. Pankevych ◽

I.A. Kolisnyk ◽

A.M. Hohol

Keyword(s):

Classical Method ◽

Third Molar ◽

Mandibular Canal ◽

Tooth Crown ◽

Wisdom Tooth ◽

Patients Âgés ◽

Advantages And Disadvantages ◽

The Third ◽

Surgical Extraction ◽

Wisdom Teeth

Impaction and malposition of wisdom teeth and associated inflammatory and tumor-like complications occur in 35-50% of the able-bodied population. The operation of surgical extraction of the third molar of the mandible is indicated for these patients and this operation is one of the most common in surgical dentistry today.Alsoasignificant indication for wisdom teeth removaliscrowding of teeth. The classic operation of surgical wisdom tooth removal, even with careful planning, can be accompanied by different intraoperative and postoperative complications. Planning of removal of the third lower molar requires an individual approachwith mandatory consideration not only of the tooth position but also the topography of the causative tooth relative to the adjacent tooth and mandibular canal. Among the surgical procedures which are used to remove wisdom teeth, in addition to the classic surgery extraction, coronectomy and germectomy should be noted. The purpose of our study was to analyze the advantages and disadvantages of different techniques used for surgical extraction of impacted and malposition wisdom teeth. 208 operations regarding the removal of the third lower molars have been performedduring 2016-2019, of which surgical wisdom teeth removal were 213, coronectomies – 23 and germectomies – 29.Patients' ages ranged from 13 to 26 years. A germectomy was performed in 13-16 years old patient, usually at the stage of a fully formed tooth crown or at the beginning of root formation. The choice of surgery in patients with fully formed roots was dependent on the ratio of the root of the tooth and mandibular canal, which was evaluated after a preliminary computer examination, taking into account the complexity of the surgery and the prognosis of complications. Acoronectomy operation was performed with the close location of the roots of the wisdom tooth with the mandibular canal, taking into account the risk of the damage of lower alveolar nerve. Germectomy and surgery of wisdom teeth removal were performed according to the classical method with cutting of mucoperiostal flaps, preparation of bone, if necessary – separation of crown and roots with subsequent removal of the germ or tooth. The crown of wisdom tooth was separated with a coronectomy, (and cut in height with insufficient access) and the tooth crown was removed, leaving the roots in the jaw. Patients were observed on the next day after surgery, a week later, and as needed. The course of the postoperative period was evaluated: the presence of pain, swelling, complications. The duration of follow-up was up to 2 years. Conclusions: To the choice of surgery in patients with impaction and malposition of wisdom teeth should be approached in a differentiated manner, taking into account topographic and anatomical features, including the ratio of the roots of the teeth to the mandibular canal and assessing the risks of possible complications. Germectomy and coronectomy surgery can be recommended as surgery of choice for orthodontic indications in the treatment of patients with crowded teeth.

Download Full-text