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

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.

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

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.

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

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.

scholarly journals Pattern of Mandibular Third Molar Impaction in Nonsyndromic 17760 Patients: A Retrospective Study among Saudi Population in Central Region, Saudi Arabia

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Mahmud Uz Zaman ◽  
Naif Salem Almutairi ◽  
Mohammed Abdulrahman Alnashwan ◽  
Shabab Mohammed Albogami ◽  
Nawaf Masad Alkhammash ◽  
...  
Keyword(s):  
Saudi Arabia ◽  
Retrospective Study ◽  
Central Region ◽  
Third Molar ◽  
University Hospital ◽  
Saudi Population ◽  
Third Molars ◽  
King Saud University ◽  
Second Molar ◽  
Mandibular Third Molars

The objective of this study was to study the incidence of type of impaction of mandibular third molars based on the classifications of Pell and Gregory and Winter, which included angulation of the tooth and level of the occlusal surface of the third molar with respect to the second molar, respectively, in a sample of Saudi population in central region. In this retrospective study, orthopantomograms (OPGs) of 17760 patients were examined, who were reported by the Dental University Hospital (DUH) at King Saud University, Riyadh, Saudi Arabia, between the years 2016 and 2020. Out of 17760 radiographs, 2187 (12.31%) patients presented with at least one impacted third molar. Out of which, 1337 (7.52%) patients had bilateral impaction and 850 (4.78%) patients had unilateral impaction ( p < 0.001 ). No gender predominance was noted in the impaction status ( p > 0.05 ). In bilateral impaction, 671 were male (50.2%) and 666 were female (49.8%). Among unilateral impaction, 394 (46.4%) were male and 456 (53.6%) were female. Mesioangular angulation was the most common pattern of impaction (65%) followed by vertical angulation in both bilateral and unilateral impactions. Level A impaction was found to be highest in both bilateral and unilateral impactions which are 48.02% and 54.0%, respectively ( p < 0.05 ). Our study highlights mesioangular impaction and level “A” as the most frequently encountered angulation and level of impaction in impacted teeth. This study result provides us useful data regarding the radiographic status of mandibular third molars in the population of Saudi Arabia.

Clinical Value of Computer-Assisted Taylor Three-dimensional External Fixation in the Treatment of Tibiofibular Fracture (Preprint)

2020 ◽  
Author(s):  
Hongfeng Sheng ◽  
Weixing Xu ◽  
Bin Xu ◽  
Hongpu Song ◽  
Di Lu ◽  
...  
Keyword(s):  
Retrospective Study ◽  
Internal Fixation ◽  
External Fixation ◽  
External Fixator ◽  
Theoretical Basis ◽  
New Technology ◽  
Three Dimensional ◽  
Computer Assisted ◽  
Clinical Value

UNSTRUCTURED The retrospective study of Taylor's three-dimensional external fixator for the treatment of tibiofibular fractures provides a theoretical basis for the application of this technology. The paper collected 28 patients with tibiofibular fractures from the Department of Orthopaedics in our hospital from March 2015 to June 2018. After the treatment, the follow-up evaluation of Taylor's three-dimensional external fixator for the treatment of tibiofibular fractures and concurrency the incidence of the disease, as well as the efficacy and occurrence of the internal fixation of the treatment of tibial fractures in our hospital. The results showed that Taylor's three-dimensional external fixator was superior to orthopaedics in the treatment of tibiofibular fractures in terms of efficacy and complications. To this end, the thesis research can be concluded as follows: Taylor three-dimensional external fixation in the treatment of tibiofibular fractures is more effective, and the incidence of occurrence is low, is a new technology for the treatment of tibiofibular fractures, it is worthy of clinical promotion.

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 Influence of Surgical Flap Design (Envelope and Szmyd) for Removal of Impacted Mandibular Third Molars on Clinical Periodontal Parameters: A Clinical Trial

2021 ◽  
Vol 18 (9) ◽  
pp. 4465
Author(s):  
Muhtada Ahmad ◽  
Zafar Ali Khan ◽  
Tahir Ullah Khan ◽  
Montaser N. Alqutub ◽  
Sameer A. Mokeem ◽  
...  
Keyword(s):  
Third Molar ◽  
Periodontal Pocket ◽  
Third Molars ◽  
Chi Square ◽  
Pocket Depth ◽  
Clinical Attachment Loss ◽  
Exact Test ◽  
Second Molar ◽  
Third Molar Extraction ◽  
Flap Design

The aim of the study was to assess the influence of flap designs (Envelope flap (EF) and Szmyd flap (SF)) for impacted mandibular third molar extraction, on periodontal pocket depth (PPD), clinical attachment loss (CAL) and bone levels (BL) of second molar. Sixty patients indicated for third molar extractions with healthy second molars were allocated into two groups: EF and SF (n = 30). Third molars were assessed for angulation, root patterns, depth of impactions and relation with ramus (Pell and Gregory classification). Extraction of third molars was performed and PPD, CAL and BL around second molars at 0, 3 and 6 month (mon) follow-ups (FU) were assessed clinically and radiographically. ANOVA, Chi-square and Fisher’s exact test were employed to compare periodontal factors between EF and SF groups, considering p ≤ 0.05 as significant. Sixty participants with a mean age of 23.22 ± 3.17 were included in the study. Based on angulation, the most common impaction in the EF and SF groups was mesio-angular (EF, 50%; SF, 36.7%). Buccal and distal PPD showed a significant increase (p < 0.001) in both EF and SF patients from baseline to 6 mon. EF patients showed significantly higher distal and buccal CAL (6.67 ± 0.18 mm; 6.91 ± 0.17 mm) and BL (7.64 ± 0.16 mm; 7.90 ± 0.15 mm) as compared to SF patients (CAL, 6.76 ± 0.26 mm; 6.91 ± 0.17 mm-BL, 7.42 ± 0.38 mm; 7.34 ± 0.34 mm) at 6 mon FU. SF showed better soft tissue attachment (PPD and CAL) and bone stability (less bone loss) around second molars compared to EF after third molar extractions regardless of the patient, tooth and operator factors.

scholarly journals Frequency and Severity of Second Molar External Root Resorption Due to the Adjacent Third Molar and Related Factors: A Cone-Beam Computed Tomography Study

2021 ◽  
Author(s):  
Shirin Sakhdari ◽  
Sara Farahani ◽  
Ehsan Asnaashari ◽  
Sahel Marjani
Keyword(s):  
Computed Tomography ◽  
Cone Beam Computed Tomography ◽  
Root Resorption ◽  
Third Molar ◽  
Cone Beam ◽  
Radiology Department ◽  
Third Molars ◽  
Related Factors ◽  
Second Molar ◽  
External Root Resorption

Objective: This study sought to assess the frequency and severity of second molar external root resorption (ERR) due to the adjacent third molar and its correlation with the position of third molar and other related factors using cone-beam computed tomography (CBCT). Materials and Methods: This cross-sectional study evaluated 320 second molars and their adjacent impacted third molars on CBCT scans of patients over 16 years, retrieved from the archives of Azad University Radiology Department. Presence/absence of second molar ERR, its location and severity (if present), and position of adjacent third molar were determined on CBCT scans, and recorded in a checklist. Data were analyzed using a logistic regression model. Results: The frequency of second molar ERR was 33.4% in the mandible and 14% in the maxilla. The severity of ERR was significantly correlated with the involved jaw (P=0.001) but had no correlation with age, gender, or depth of impaction of adjacent third molar (P>0.05). The mesioangular and horizontal positions of impacted third molars had a significant correlation with the frequency of second molar ERR (P<0.006). Conclusion: According to the results of this study, ERR occurring in second molars adjacent to third molars is common, especially in the mandible. Mesially inclined third molars have a greater potential of being associated with ERR in second molars.

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

2018 ◽  
Vol 52 (4) ◽  
pp. 394-401 ◽  
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.

scholarly journals Nonsurgical and nonprosthetic camouflage treatment of skeletal Class II open bite with bilaterally missing lower first molars

2018 ◽  
Vol 89 (3) ◽  
pp. 505-517. ◽  
Author(s):  
Tung Nguyen ◽  
Eui Seon Baek ◽  
Soonshin Hwang ◽  
Kyung-Ho Kim ◽  
Chooryung J. Chung
Keyword(s):  
Treatment Outcome ◽  
Three Dimensional ◽  
Class Ii ◽  
Open Bite ◽  
Third Molars ◽  
Second Molar ◽  
Skeletal Class ◽  
Long Term Stability ◽  
Skeletal Class Ii

ABSTRACT This report illustrates the successful nonsurgical and nonprosthetic camouflage treatment of a skeletal Class II open bite malocclusion combined with missing mandibular first molars bilaterally. In the mandible, the second and third molars were uprighted and protracted, substituting for the missing first molars. In the maxilla, anterior bodily retraction and full-arch intrusion were achieved following premolar and second molar extraction, which also induced autorotation of the mandible. The treatment outcome and prognosis were confirmed with three-dimensional superimposition techniques, along with long-term stability.

scholarly journals Relation between mandibular third molar and mandibular canal as assessed by three-dimensional Computed tomographic reconstruction.

2000 ◽  
Vol 46 (5) ◽  
pp. 251-261 ◽  
Author(s):  
Toshinori TANAKA ◽  
Kei MURAKAMI ◽  
Tsuyoshi KISHIDA ◽  
Takatoshi ITOH ◽  
Yasuhiko MORITA ◽  
...  
Keyword(s):  
Tomographic Reconstruction ◽  
Three Dimensional ◽  
Third Molar ◽  
Mandibular Canal ◽  
Computed Tomographic ◽  
Mandibular Third Molar
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