946 D3000 new imprint Word template Vol 13, No 1 (2025) ISSN 2167-8677 (online) DOI 10.5195/d3000.2025.946 http://dentistry3000.pitt.edu Distribution and Angulation Pattern of Impacted Mandibular Third Molars Iman Ali Khalil Al-Obaidi Ashur University, Baghdad, Iraq Abstract Objec2ve: The objecDve of this study was to determine the distribuDon of impacted mandib- ular third molars on digital panoramic radiographs, based on sex of the paDent, side, level of impacDon, relaDonship with the mandibular ramus, and angulaDon paRern of impacDon. Ma- terial and Methods: This study analysed 98 people aged 18 and above with 153 impacted mandibular third molars who were treated at the Department of Oral and Maxillofacial Radi- ology at Ashur University's College of DenDstry. PaDents were categorised by sex, right or leZ side, depth of impacDon, relaDonship with the mandibular ramus, and angulaDon paRerns. Results: The only significant difference found was related to the leZ side impacDon depth with females having more level C impacDons than males. Conclusion: The distribuDon of im- pacted mandibular third molars were mostly mesioangular, followed by horizontal angula- Don, impacDon level C, and class II. Open Access Cita%on: Al-Obaidi IAK. (2025) Distribu%on and Angula- %on Pa>ern of Impacted Mandibular Third Molars. Den- %stry 3000. 1:a001 doi:10.5195/d3000.2025.946 Received: May 22, 2025 Accepted: June 26, 2025 Published: August 12, 2025 Copyright: ©2025 Al-Obaidi. This is an open access ar%- cle licensed under a Crea%ve Commons A>ribu%on Work 4.0 United States License. Email: iman.ali@au.edu.iq Introduc)on Dental impacDon refers to a tooth that has not fully or parDally erupted within the jawbone or under gum Dssue. Dental impacDon can occur in all teeth, but the most common teeth of im- pacDons are the third molars [1]. The third mo- lar impacDons account for 98% of all types of impacted teeth [2]. The impacDon rate varies between different geographics from 18.97% to 30.8% within the Gulf region but 68.6% in East Asia [3,4]. Molar impacDons have many causes, such as insufficient skeletal growth, mucosal thickness over the growing tooth, macrodonDa, lack of space or systemic condiDons such as Down’s syndrome. There are studies that show varia- Don based on diet as there was differences be- tween the mandibular jaw size between medi- aeval to post-mediaeval peoples [5]. This oc- curred due to biomechanical forces, which sDmulated craniofacial growth and develop- ment. In addiDon, there is a variaDon in erupDon and posiDon of the third molar, which can be influenced by ethnicity, masDcatory ef- fecDveness, and inherited factors [6]. ImpacDon complicaDons include crowding, car- ies, pericoroniDs, resorpDon of adjacent tooth roots, face pain, temporomandibular joint dys- funcDon, and the most prevalent condiDon, denDgerous cyst or tumour [7]. Life-threaten- ing is the transformaDon of the cysDc wall into squamous cell carcinoma [1]. The early diagno- sis of impacted teeth can avoid future maloc- clusions and lesions [8]. IdenDfying and manag- ing these dental anomalies at an early stage can avert complicaDons. Regular dental check- ups, including radiographic evaluaDons, play a pivotal role in the Dmely detecDon and treat- ment of impacted teeth. Panoramic radiography classificaDon is an es- senDal component of treatment planning for the operaDon of removal of the mandibular third molar, which is sDll a comprehensive clin- ical and radiographic evaluaDon. The paDent should have a complete case history that in- cludes detailed systemic and local evaluaDon. Age (increasing difficulty for extracDon with age) and sex (incidence of increase of scleroDc bone in males with age/consider the incidence of post-menopausal osteoporosis in females) should also be noted [9]. Panoramic radio- graph is based on some sort of classificaDon and in this study we established the classifica- Don on Pell, Gregory, and Winter, are crucial for determining third molar posiDon, depth, and bone covering, as well as assessing surgical treatments' challenges [6,10,11]. In this study, we focused only on the lower third mandibular molar and uDlized different classificaDon to organize different types of im- pacDons of the molars. These impacDons were then compared between different sexes. Material and Methods A cross-secDonal observaDonal study was un- dertaken at Ashur University's Dental DistribuDon and AngulaDon PaRern of Impacted Mandibular Third Molars Vol 13, No 1 (2025) DOI 10.5195/d3000.2025.946 http://dentistry3000.pitt.edu 2 Radiology Clinics - Department of Oral and Maxillofacial Radiology in Baghdad, Iraq. We reviewed all panoramic radiographs at Ashur University's Dental Radiology Clinics from No- vember 2023 to November 2024. A total of 153 impacted mandibular third molars were evalu- ated in 98 individuals who were 18 years or above. These data were further separated into two groups based on sex. The examinaDon of the lower third mandibular molar was performed using digital orthopanto- mography (panoramic radiography). These im- ages were assessed using Pell, Gregory, and Winter for evaluaDng the depth, relaDonship to ramus and angulaDon of the teeth. During the study, all paDents were handled by the same operator, and panoramic radiographs were obtained using the same machine. Digital panoramic exposures were achieved using con- venDonal techniques. Two examiners exam- ined all panoramic radiographs and conducted analyses. Study design. In this study we analysed all pan- oramic radiographs at Ashur University's Den- tal Radiology Clinics from November 2023 to November 2024 using data collected during a one-year period. Radiographs from normal dental examinaDons were randomly obtained from the Department of Oral and Maxillofacial Radiology archives. The study excluded pa- Dents with incomplete root formaDon or de- formed mandibular third molar roots, as well as those without mandibular second molars. This study only included high-quality radio- graphs with clear reproducDon of teeth and no superimposiDon (example in Figure 1). PaDents were divided into groups based on their sex, right or leZ side, depth of impacDon, relaDon- ship with the mandibular ramus, and angula- Don paRerns. Digital panoramic radiographs were taken us- ing the Myray Hyperion X9 Pro machine at 70 Kvp, 7mA, and 12.7 seconds exposure duraDon at our Department of Oral and Maxillofacial Ra- diology. Two examiners viewed radiographs with the iRYS soZware version 14.0.1. The col- lected data were analysed using staDcal SPSS soZware version 29.0.1.1. Study parameters. The following criteria were assessed in this study (Figures 2 and 3): 1. The angulaDon of the impacted third molar teeth was categorized using Winter's classifica- Don [6,12]. 2.The Pell and Gregory classificaDon was used to define the depth of the impacted third molar teeth [11,13]. 3.The Pell and Gregory categorizaDon was used to define the relaDonship between an im- pacted third molar and ramus [11,13]. Winter’s ClassificaDon classified third molar impacDons as mesioangular, distoangular, horizontal, verDcal, buccal, and others [6]. We used another classificaDon for the depth and relaDon to ramus neck of the jaw. Pell and Gregory's A, B, and C raDngs are based on their depth and relaDon with the mandible's ramus [11]. The following definiDons were used in this study for impacDon and angulaDon of impac- Don. A tooth was termed impacted if its occlu- sal plane was below that of the adjacent tooth and bone level. A parDally or semi-impacted tooth is one that has parDally erupted but sDll in the line of occlusion. To assess the inclina- Don of an impacted mandibular third molar, the angulaDon between the longer axis and the neighbouring second molar teeth was meas- ured using Winter’s classificaDon. Impac3on: The third molar must not have a funcDonal occlusion when the root formaDon is finished to be classified as impacted. Depth of impac3on: The Pell and Gregory clas- sificaDon categorizes the cementoenamel juncDon (CEJ) of the third molar with respect to bone level: Level A - Not buried in bone; Level B - ParDally buried in bone if any part of the CEJ was lower than bone level; and level C - Com- pletely buried in. Rela3onship with the mandibular ramus: The Pell and Gregory classificaDon categorizes the distal surface of the third molar crown in rela- Don to the anterior border of the ascending ra- mus into the following posiDons: Class I is an- terior to the anterior border, Class II is half of the crown covered by the anterior border, and Class III is the enDre crown covered by the an- terior border. Angulation of impaction: Winter's classification categorizes the angle between the longitudinal axis of the second and third molars, measured with an orthodontic protractor. Vertical impac- tion ranges from 10 to -10, whereas mesioan- gular impaction ranges from 11 to -79, horizon- tal impaction ranges from 80 to 100, distoan- gular impaction ranges from -11 to -79, others range from 111 to -80, and buccolingual impac- tion occurs when the crown and roots are su- perimposed. Results Unilateral vs. bilateral Table1 presents the distribuDon of unilateral and bilateral mandibular third molar impac- Dons based on sex. Among the 98 cases, 65 were males and 33 were females. Unilateral and bilateral impacDons were more frequent in males than females, but that difference was not staDsDcally significant (p = 0.84). The depth of impacDon was classified using the Pell & Gregory scale. The results in Table 2 in- dicate that Level C impacDons (deepest) were the most common in both sexes with approxi- mately half of the cases. For the leZ side depth, Level B impacDons were most common in males (38.5%), while Level C impacDons were predominant in females (60.6%), indicaDng that females tend to experience deeper impac- Dons compared to males (p=0.048). The classification of impacted molars based on their relationship with the mandibular ramus was evaluated as seen in Table 3. Most impac- tions fell under Class II (69.2% in males, 66.7% in females), indicating that the impacted mo- lars were partially covered by the anterior bor- der of the ramus. Winter’s classificaDon was applied to evaluate the angulaDon of impacted third molars. The most common angulaDon type observed was mesioangular impacDon, occurring in 55.3% of males and 44.7% of females as seen in Table 4. Horizontal impacDons were notably more fre- quent in males (82.1%) compared to females (17.9%), although not staDsDcally significant (p=0.168). When analysing angulaDon paRerns on the leZ side, mesioangular impacDons were again the most frequent (32.3% in males, 39.4% in females). InteresDngly, horizontal im- pacDons were more frequent in males (75%) than females (25%), whereas distoangular im- pacDons were only seen in females (9.1%) (p=0.14). Discussion There was no significant difference between males and females when it came to unilateral and bilateral impacDon. The results for right sided depth, ramus relaDonship and angulaDon classificaDon showed that there was no signifi- cant variaDon between males and females. The leZ side results were also not significant differ- ent when it came to the categorizaDon of ra- mus and angulaDon of the third molar, but there was a significant variaDon when it came to the leZ sided depth classificaDon. The lack of significance is likely due to small sample size. Other factors that may impact the actual devel- opment of teeth in humans include geneDc var- iaDon, aging, developmental disorders, and di- etary factors. It is to be noted that there is a sexual dimorphism in tooth size, which has ge- neDc inheritance, testosterone, and evoluDon- ary selecDon, and hormonal secreDon influ- ences. Growth hormone, testosterone, pro- motes growth of teeth size whereas estrogen would limit the jaw size growth and teeth size [14-16]. Many genes play a role in crown size [14]. As an example, FGF10 and FGF13 were associated to molar size discrepancies [16]. There is a de- crease in jaw size with age between 18 and 40 years, which may relate to a decrease in testos- terone and the impact of growth hormone, which makes male jaw to be bigger in size com- parison to the female jaw size [17]. There is DistribuDon and AngulaDon PaRern of Impacted Mandibular Third Molars Vol 13, No 1 (2025) DOI 10.5195/d3000.2025.946 http://dentistry3000.pitt.edu 3 also the implicaDon of dietary habit in final jaw sizes [18,19]. Lack of differences in the impaction of third molars between males and females agrees with previous data [20,21] . Bilateral impac- tions are more common than unilateral ones and these differences are independent from sex [22,23]. Conclusions ImpacDon of the mandibular third molars is common among Iraqis. It has been noDced that males had more impacted molars compared to females, but the difference was not significant. The most common paRern for impacted man- dibular third molars was mesioangular, fol- lowed by horizontal angulaDon, impacDon level C, and class II. Males experienced more unilateral impacDons and slightly more bilat- eral impacDons than females. Comparing our data to various populaDons revealed similari- Des in some characterisDcs, such as angulaDon and connecDon to ramus, but overall results vary. This study has been characterized by a high fre- quency of lower third molar impacDon, parDc- ularly in males. This high frequency signifies that an increasing number of individuals are re- taining the impacted third molars. References 1. Carter K, Worthington S. Predictors of Third Molar Impaction: A Systematic Review and Meta-analysis. J Dent Res. 2016;95(3):267- 76.https://doi.org/10.1177/0022034515615857 2. Santosh P. Impacted Mandibular Third Molars: Review of Literature and a Proposal of a Combined Clinical and Radiological ClassiVication. Ann Med Health Sci Res. 2015;5(4):229- 34.https://doi.org/10.4103/2141-9248.160177 3. Quek SL, Tay CK, Tay KH, Toh SL, Lim KC. Pattern of third molar impaction in a Singapore Chinese population: a retrospective radiographic survey. Int J Oral Maxillofac Surg. 2003;32(5):548- 52 4. Hassan AH. Pattern of third molar impaction in a Saudi population. Clin Cosmet Investig Dent. 2010;2:109- 13.https://doi.org/10.2147/CCIDEN.S12394 5. Rando C, Hillson S, Antoine D. Changes in mandibular dimensions during the mediaeval to post-mediaeval transition in London: a possible response to decreased masticatory load. Arch Oral Biol. 2014;59(1):73- 81.https://doi.org/10.1016/j.archoralbio.2013.1 0.001 6. Winter G. Principles of exodontias as applied to the impacted third molar 1st ed. St. Louis American medical books 1926. Contemporary Oral and Maxillofacial Sugery. 1993;2 7. Fayad JB, Levy JC, Yazbeck C, Cavezian R, Cabanis E-A. Eruption of third molars: relationship to inclination of adjacent molars. American journal of orthodontics and dentofacial orthopedics. 2004;125(2):200-2 8. da Silva Menezes CG, Sartoretto SC, Louro RS, de Moraes JB, Moraschini V. Prevalence of Impacted Teeth: A Radiographical Retrospective Rio de Janeiro Population-Based Study. J Maxillofac Oral Surg. 2024;23(1):75- 80.https://doi.org/10.1007/s12663-023-02021- 3 9. Bhargava D. Clinical and radiographic assessment for impacted mandibular third molars. Transalveolar Extraction of the Mandibular Third Molars: CRC Press; 2022. p. 39-49. 10. Khouri C, Aoun G, Khouri C, Saade M, Salameh Z, Berberi A. Evaluation of Third Molar Impaction Distribution and Patterns in a Sample of Lebanese Population. J Maxillofac Oral Surg. 2022;21(2):599- 607.https://doi.org/10.1007/s12663-020- 01415-x 11. Pell GJ. Impacted mandibular third molars, classiVication and modiVied technique for removal. Dental Digest. 1933;39:330-8 12. Lei Y, Chen X, Wang Y, Tang R, Zhang B. A Lightweight Knowledge-Distillation-Based Model for the Detection and ClassiVication of Impacted Mandibular Third Molars. Applied Sciences. 2023;13(17).https://doi.org/10.3390/app13179 970 13. Eshghpour M, Nezadi A, Moradi A, Shamsabadi RM, Rezaei NM, Nejat A. Pattern of mandibular third molar impaction: A cross- sectional study in northeast of Iran. Niger J Clin Pract. 2014;17(6):673- 7.https://doi.org/10.4103/1119-3077.144376 14. Dempsey PJ, Townsend GC. Genetic and environmental contributions to variation in human tooth size. Heredity (Edinb). 2001;86(Pt 6):685-93.https://doi.org/10.1046/j.1365- 2540.2001.00878.x 15. Christensen MM, Hallikas O, Das Roy R, Vaananen V, Stenberg OE, Hakkinen TJ, et al. The developmental basis for scaling of mammalian tooth size. Proc Natl Acad Sci U S A. 2023;120(25):e2300374120.https://doi.org/10. 1073/pnas.2300374120 16. Maranon-Vasquez GA, Vieira AR, Dos Santos LV, Cunha AS, Weiss SG, Araujo MTS, et al. FGF10 and FGF13 genetic variation and tooth-size discrepancies. Angle Orthod. 2021;91(3):356- 62.https://doi.org/10.2319/060920-531.1 17. Tsiopas N, Nilner M, Bondemark L, Bjerklin K. A 40 years follow-up of dental arch dimensions and incisor irregularity in adults. Eur J Orthod. 2013;35(2):230- 5.https://doi.org/10.1093/ejo/cjr121 18. Kahn S, Ehrlich P, Feldman M, Sapolsky R, Wong S. The Jaw Epidemic: Recognition, Origins, Cures, and Prevention. Bioscience. 2020;70(9):759- 71.https://doi.org/10.1093/biosci/biaa073 19. Menendez L, Bernal V, Novellino P, Perez SI. Effect of bite force and diet composition on craniofacial diversiVication of Southern South American human populations. Am J Phys Anthropol. 2014;155(1):114- 27.https://doi.org/10.1002/ajpa.22560 20. Dachi SF, Howell FV. A survey of 3,874 routine full-mouth radiographs: II. A study of impacted teeth. Oral Surgery, Oral Medicine, Oral Pathology. 1961;14(10):1165-9 21. Al-Delaimi TN, Abood SW, Khalil AA. The evaluation of impacted third molars using a panoramic radiograph. Al-Anbar Med J. 2010;8(1):26-33 22. Shahbaz S, Khan M. Evaluation of mandibular third molar impaction distribution on OPG: a digital radiographic study. International Journal of Applied Dental Sciences. 2017;3:393-6 23. Al-Anqudi SM, Al-Sudairy S, Al-Hosni A, Al-Maniri A. Prevalence and Pattern of Third Molar Impaction: A retrospective study of radiographs in Oman. Sultan Qaboos Univ Med J. 2014;14(3):e388-92. DistribuDon and AngulaDon PaRern of Impacted Mandibular Third Molars Vol 13, No 1 (2025) DOI 10.5195/d3000.2025.946 http://dentistry3000.pitt.edu 4 Figure 1. An orthopantomogram showing an impacted mandibular third molar. Figure 2. The impacDon depth, ramus relaDonship, and angulaDon classificaDon of mandibular third molars take from paRern of mandibular third molar impacDon: A cross-secDonal study in northeast of Iran” paper wriRen by Eshghpour and colleagues. DistribuDon and AngulaDon PaRern of Impacted Mandibular Third Molars Vol 13, No 1 (2025) DOI 10.5195/d3000.2025.946 http://dentistry3000.pitt.edu 5 Figure 3. Winter’s classificaDon taken from arDcle “A Lightweight Knowledge-DisDllaDon-Based Model for the DetecDon and ClassificaDon of Impacted Mandibular Third Molars” by Lei and colleagues. Table 1. Comparison between the unilateral/bilateral impacDon by sex. Side Total Unilateral Bilateral Sex Male 29 (67.4%) 36 (65.5%) 65 Female 14 (32.6%) 19 (32.6%) 33 Total 43 (100%) 55 (100%) 98 X2 = 0.043, p = 0.836 DistribuDon and AngulaDon PaRern of Impacted Mandibular Third Molars Vol 13, No 1 (2025) DOI 10.5195/d3000.2025.946 http://dentistry3000.pitt.edu 6 Table 2. Comparison of the impacDon depth according to the Pell & Gregory category by sex. Sex Male Female Count Count Right side ImpacDon Depth N/A 11 (16.9%) 7 (21.2%) A 0 (0%) 0 (0%) B 19 (29.2%) 8 (24.2%) C 35 (53.8%) 18 (54.5%) X2 = 0.419 (p = 0.811) LeZ Side ImpacDon Depth N/A 18 (27.7%) 7 (21.2%) A 1 (1.5%) 0 (0.0%) B 25 (38.5%) 6 (18.2%) C 21 (32.3%) 20 (60.6%) X2 = 7.903 (p =0.048) Table 3. Comparison of the impacDon ramus relaDonship according to the Pell & Gregory category by sex. N/A means the absence of the impacDon related to the ramus. Sex Male Female Count Count Right side Ramus RelaDonship N/A 11 (16.9%) 7 (21.2%) I 9 (13.8%) 3 (9.1%) II 45 (69.2%) 22 (66.7%) III 0 (0%) 1(3%) X2 = 2.614 (p =0.455) LeZ Side Ramus RelaDonship N/A 18 (27.7%) 7 (21.2%) I 11 (16.9%) 5 (15.2%) II 35 (53.8%) 21 (63.6%) III 1 (1.5%) 0 (0%) X2 = 1.277 (p = 0.735) DistribuDon and AngulaDon PaRern of Impacted Mandibular Third Molars Vol 13, No 1 (2025) DOI 10.5195/d3000.2025.946 http://dentistry3000.pitt.edu 7 Table 4. Comparison of the impacDon angulaDon according to the Winter’s classificaDon by sex. Sex Male Female Count Count Right side AngulaDon N/A 11 (16.9%) 7 (21.2%) VerDcal 8 (12.3%) 4 (12.1%) Horizontal 23 (35.4%) 5 (15.2%) Distoangular 0 (0%) 0 (0%) Mesioangular 21 (32.3%) 17 (51.5%) Buccolingual 2 (3.1%) 0 (0%) Other 0 (0%) 0 (0%) Total 65 33 X2 = 6.454 (p = 0.168) LeZ Side AngulaDon N/A 18 (27.7%) 7 (21.2%) VerDcal 4 (6.2%) 3 (9.1%) Horizontal 21 (32.3%) 7 (21.2%) Distoangular 0 (0%) 3 (9.1%) Mesioangular 21 (32.3%) 13 (39.4%) Buccolingual 1(1.5%) 0 (0%) Other 0 (0%) 0 (0%) X2 = 8.301 (p = 0.14)