Influence of impacted mandibular third molars on pathological changes on themselves and adjacent tissues across different age groups

a cross-sectional study

Authors

  • Xiaoyue Ge Xi'an Medical University, School of Stomatology, Engineering Research Center of Oral and Maxillary System Disease
  • Yixiao Cui Xi'an Medical University, School of Stomatology, Engineering Research Center of Oral and Maxillary System Disease
  • Ning Li Xi'an Medical University, School of Stomatology, Engineering Research Center of Oral and Maxillary System Disease
  • Tianyang Lv Xi'an Medical University, School of Stomatology, Engineering Research Center of Oral and Maxillary System Disease
  • Yuntong Liang Xi'an Medical University, School of Stomatology, Engineering Research Center of Oral and Maxillary System Disease
  • Haochen Wu Xi'an Medical University, School of Stomatology, Engineering Research Center of Oral and Maxillary System Disease
  • Yuxuan Gu Xi'an Medical University, School of Stomatology, Engineering Research Center of Oral and Maxillary System Disease
  • Meiting Li Xi'an Medical University, School of Stomatology, Engineering Research Center of Oral and Maxillary System Disease
  • Changkui Liu Xi'an Medical University, School of Stomatology, Engineering Research Center of Oral and Maxillary System Disease
  • Yayuan Guo Xi'an Medical University, School of Stomatology, Engineering Research Center of Oral and Maxillary System Disease
  • Kaijin Hu Xi'an Medical University, School of Stomatology, Engineering Research Center of Oral and Maxillary System Disease

DOI:

https://doi.org/10.1590/1678-7765-2025-0677

Keywords:

Third molar, Alveolar bone loss, Cone-beam computed tomography

Abstract

Objective  To investigate the effects of different types of impacted mandibular third molar (IMTM) on lesions in situ and on adjacent tissues at different ages. Methodology  Cone Beam Computed Tomography (CBCT) images of 1007 IMTM cases were retrospectively analyzed. Associations between age, gender, impaction type, distal alveolar bone condition of mandibular second molar (MSM), IMTM-MSM contact status and occurrence of lesions on IMTM and its adjacent tissues were evaluated using Pearson’s chi-squared test and Fisher’s exact test. Results  MSM distal alveolar bone defects showed the highest incidence among all IMTM-related lesions (79.2%), followed by MSM distal external root resorption (ERR) (25.5%) and MSM distal caries (10.4%). Mesioangular (96.2%, p<0.001) and horizontal (95.9%, p<0.001) IMTM were associated with more severe bone defects and the incidence increased with age. IMTM-MSM surface-to-surface contact was significantly associated with MSM distal caries severity (12.5%, p<0.001) and distal ERR (29.5%, p<0.001). Inflammatory resorption of MSM distal alveolar bone was significantly correlated with MSM distal caries (47.1%, p<0.001), ERR (36.5%, p<0.05), distal alveolar bone defects (100%, p<0.001), and IMTM caries (14.1%, p<0.05). Study design followed the STROBE guidelines. Conclusion  Mesioangular impaction, horizontal impaction, MSM-IMTM surface-to-surface contact, and MSM distal alveolar bone in a state of inflammatory resorption greatly affect lesions on IMTM and its surrounding tissues. These findings suggest the prophylactic extraction in young adults (18–25 years) with high-risk impactions, while recommending observation or cautious management for asymptomatic older patients without signs of inflammatory bone resorption.

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References

1- Butzin S. To prophylactically extract or not to extract partially erupted mesio-angularly impacted lower third molars? Br Dent J. 2021;231(8):445-8. doi: 10.1038/s41415-021-3561-3

» https://doi.org/10.1038/s41415-021-3561-3

2- Vranckx M, Fieuws S, Jacobs R, Politis C. Prophylactic vs. symptomatic third molar removal: effects on patient postoperative morbidity. J Evid Based Dent Pract. 2021;21(3):101582. doi: 10.1016/j.jebdp.2021.101582

» https://doi.org/10.1016/j.jebdp.2021.101582

3- Almendros-Marqués N, Alaejos-Algarra E, Quinteros-Borgarello M, Berini-Aytés L, Gay-Escoda C. Factors influencing the prophylactic removal of asymptomatic impacted lower third molars. Int J Oral Maxillofac Surg. 2008;37(1):29-35. doi: 10.1016/j.ijom.2007.06.008

» https://doi.org/10.1016/j.ijom.2007.06.008

4- Mathai BC, Talaat W, Keni PK, Madgavkar M. Third molars in dentistry: extract or not to, what is the evidence. Dent Clin North Am. 2026;70(1):1-14. doi: 10.1016/j.cden.2025.07.002

» https://doi.org/10.1016/j.cden.2025.07.002

5- Gojayeva G, Tekin G, Saruhan Kose N, Dereci O, Kosar YC, Caliskan G. Evaluation of complications and quality of life of patient after surgical extraction of mandibular impacted third molar teeth. BMC Oral Health. 2024;24(1):131. doi: 10.1186/s12903-024-03877-8

» https://doi.org/10.1186/s12903-024-03877-8

6- Fernandes IA, Galvão EL, Gonçalves PF, Falci SG. Impact of the presence of partially erupted third molars on the local radiographic bone condition. Sci Rep. 2022;12(1):8683. doi: 10.1038/s41598-022-12729-w

» https://doi.org/10.1038/s41598-022-12729-w

7- Skitioui M, Jaoui D, Haj Khalaf L, Touré B. Mandibular second molars and their pathologies related to the position of the mandibular third molar: a radiographic study. Clin Cosmet Investig Dent. 2023;15:215-23. doi: 10.2147/CCIDE.S420765

» https://doi.org/10.2147/CCIDE.S420765

8- Poszytek D, Górski B. Relationship between the status of third molars and the occurrence of dental and periodontal lesions in adjacent second molars in the Polish population: a radiological retrospective observational study. J Clin Med. 2023;13(1):20. doi: 10.3390/jcm13010020

» https://doi.org/10.3390/jcm13010020

9- Alqahtani AS, Najmuddin M, Saheb SA, Aljabri M, Abuhadi BM, Basheri AA, et al. Pattern of mandibular third molar impaction and distal pathologies of the second molar in the presence and absence of the mandibular third molar among Jazan population, Saudi Arabia: a radiographic evaluation. Eur J Gen Dent. 2026;15(1):68-73. doi: 10.1055/s-0045-1802342

» https://doi.org/10.1055/s-0045-1802342

10- Altan A, Akbulut N. Does the angulation of an impacted mandibular third molar affect the prevalence of preoperative pathoses? J Dent (Shiraz). 2019;20(1):48-52. doi: 10.30476/DENTJODS.2019.44563

» https://doi.org/10.30476/DENTJODS.2019.44563

11- Haddad Z, Khorasani M, Bakhshi M, Tofangchiha M, Shalli Z. Radiographic position of impacted mandibular third molars and their association with pathological conditions. Int J Dent. 2021;2021:8841297. doi: 10.1155/2021/8841297

» https://doi.org/10.1155/2021/8841297

12- Ndiaye ML, Gassama BC, Niang SO, Lecor PA, Ndiaye A, Toure B. Distal pathologies of the second molar in the presence of the mandibular third molar: study by panoramic radiography. Adv Oral Maxillofac Surg. 2021;3:100090. doi: 10.1016/j.adoms.2021.100090

» https://doi.org/10.1016/j.adoms.2021.100090

13- Arandi NZ, Jarrar A. Association between mandibular third molar impactions and distal carious lesions on the adjacent second molars: a cross-sectional study. J Int Med Res. 2025;53(3):3000605251324489. doi: 10.1177/03000605251324489

» https://doi.org/10.1177/03000605251324489

14- Yildirim H, Büyükgöze-Dindar M. Investigation of the prevalence of impacted third molars and the effects of eruption level and angulation on caries development by panoramic radiographs. Med Oral Patol Oral Cir Bucal. 2022;27(2):e106-12. doi: 10.4317/medoral.25013

» https://doi.org/10.4317/medoral.25013

15- Kawsankar K, Mahindra U, Kale L, Motwani D, Gaikwad R, Pawar N, et al. A retrospective study of correlation of third molar impaction pattern with distal caries in abutting second molar. Int J Innov Sci Res Technol. 2025;10(3):3171-4. doi: 10.38124/ijisrt25mar1334

» https://doi.org/10.38124/ijisrt25mar1334

16- Hamad SA. External root resorption of second molars due to impacted third molars. J Clin Exp Dent. 2024;16(12):e1489-94. doi: 10.4317/jced.62080

» https://doi.org/10.4317/jced.62080

17- Belam A, Rairam SG, Patil V, Ratnakar P, Patil S, Kulkarni S. Evaluation of detrimental effects of impacted mandibular third molars on adjacent second molars: a retrospective observational study. J Conserv Dent. 2023;26(1):104-7. doi: 10.4103/jcd.jcd_341_22

» https://doi.org/10.4103/jcd.jcd_341_22

18- Prasanna Kumar D, Sharma M, Vijaya Lakshmi G, Subedar RS, Nithin VM, Patil V. Pathologies associated with second mandibular molar due to various types of impacted third molar: a comparative clinical study. J Maxillofac Oral Surg. 2022;21(4):1126-39. doi: 10.1007/s12663-021-01517-0

» https://doi.org/10.1007/s12663-021-01517-0

19- Akkitap MP, Gumru B. Can the position of the impacted third molars be an early risk indicator of pathological conditions? A retrospective cone-beam computed tomography study. J Oral Maxillofac Res. 2023;14(2):e3. doi: 10.5037/jomr.2023.14203

» https://doi.org/10.5037/jomr.2023.14203

20- Chen Y, Zheng J, Li D, Huang Z, Huang Z, Wang X, et al. Three-dimensional position of mandibular third molars and its association with distal caries in mandibular second molars: a cone beam computed tomographic study. Clin Oral Investig. 2020;24(9):3265-73. doi: 10.1007/s00784-020-03203-w

» https://doi.org/10.1007/s00784-020-03203-w

21- Smailiene D, Trakiniene G, Beinoriene A, Tutliene U. Relationship between the position of impacted third molars and external root resorption of adjacent second molars: a retrospective CBCT study. Medicina (Kaunas). 2019;55(6):305. doi: 10.3390/medicina55060305

» https://doi.org/10.3390/medicina55060305

22- Leung YY, Hung KF, Li DT, Yeung AW. Application of cone beam computed tomography in risk assessment of lower third molar surgery. Diagnostics (Basel). 2023;13(5):919. doi: 10.3390/diagnostics13050919

» https://doi.org/10.3390/diagnostics13050919

23- Moreira-Souza L, Butini Oliveira L, Gaêta-Araujo H, Almeida-Marques M, Asprino L, Oenning AC. 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. Dentomaxillofac Radiol. 2022;51(3):20210217. doi: 10.1259/dmfr.20210217

» https://doi.org/10.1259/dmfr.20210217

24- Dias MJ, Franco A, Junqueira JL, Fayad FT, Pereira PH, Oenning AC. Marginal bone loss in the second molar related to impacted mandibular third molars: comparison between panoramic images and cone beam computed tomography. Med Oral Patol Oral Cir Bucal. 2020;25(3):e395-402. doi: 10.4317/medoral.23443

» https://doi.org/10.4317/medoral.23443

25- Tunç SK, Koc A. Evaluation of risk factors for external root resorption and dental caries of second molars associated with impacted third molars. J Oral Maxillofac Surg. 2020;78(9):1467-77. doi: 10.1016/j.joms.2020.04.041

» https://doi.org/10.1016/j.joms.2020.04.041

26- Zhou W, Xiong Z, Fan J, Yang T, Gu Y. Cone-beam computed tomographic investigation of the association between impacted mandibular third molars and the development of distal caries in adjacent second molars in a Chinese population. Heliyon. 2024;10(23):e40655. doi: 10.1016/j.heliyon.2024.e40655

» https://doi.org/10.1016/j.heliyon.2024.e40655

27- Sakhdari S, Farahani S, Asnaashari E, Marjani S. Frequency and severity of second molar external root resorption due to the adjacent third molar and related factors: a cone-beam computed tomography study. Front Dent. 2021;18:36. doi: 10.18502/fid.v18i36.7561

» https://doi.org/10.18502/fid.v18i36.7561

28- Cui L, Jiang E, Liu Z, Li J. Relationship between the impacted mandibular third molar and adjacent second molar external root resorption by cone-beam computed tomography analysis. Med Oral Patol Oral Cir Bucal. 2024;29(1):e27-35. doi: 10.4317/medoral.26044

» https://doi.org/10.4317/medoral.26044

29- Gürses G, Akçakaya A, Akti A, Aydin O. The effect of impacted third molars on second molar external root resorption, a cross-sectional cone beam computed tomography study. Med Oral Patol Oral Cir Bucal. 2023;28(6):e504-11. doi: 10.4317/medoral.25860

» https://doi.org/10.4317/medoral.25860

30- Kou Z, Zhang W, Li C, Zhang Y, Song Z, Zou Y, et al. A prediction model for external root resorption of the second molars associated with third molars. Int Dent J. 2025;75(1):195-205. doi: 10.1016/j.identj.2024.09.031

» https://doi.org/10.1016/j.identj.2024.09.031

31- Eren I, Cosan Ata G, Eren H. Retrospective analysis of the prevalence of external root resorption in the adjacent mandibular second molar due to impacted mandibular third molar using cone-beam computed tomography. Essent Dent. 2025;4(1):0018. doi: 10.5152/EssentDent.2025.25018

» https://doi.org/10.5152/EssentDent.2025.25018

32- Pell GJ. Impacted mandibular third molars, classification and modified technique for removal. Dent Dig. 1933;39:330-8

33- Schriber M, Rivola M, Leung YY, Bornstein MM, Suter VG. Risk factors for external root resorption of maxillary second molars due to impacted third molars as evaluated using cone beam computed tomography. Int J Oral Maxillofac Surg. 2020;49(5):666-72. doi: 10.1016/j.ijom.2019.09.016

» https://doi.org/10.1016/j.ijom.2019.09.016

34- Zeng S, Guo F, Wang J. [Evaluation of risk factors of the distal alveolar bone resorption of the second molar associated with impacted mandibular third molar by cone-beam computed tomography]. Chin J Stomatol Res. 2021;15(1):13-7. Chinese. doi: 10.3877/cma.j.issn.1674-1366.2021.01.003

» https://doi.org/10.3877/cma.j.issn.1674-1366.2021.01.003

35- Li K, Xu W, Zhou T, Chen J, He Y. The radiological and histological investigation of the dental follicle of asymptomatic impacted mandibular third molars. BMC Oral Health. 2022;22(1):642. doi: 10.1186/s12903-022-02681-6

» https://doi.org/10.1186/s12903-022-02681-6

36- Barroso M, Arriola-Guillén LE, Rodríguez-Cárdenas YA, Ruíz-Mora GA, Guerrero ME, Flores-Mir C. Tridimensional assessment of the dental follicle dimensions of impacted mandibular third molars using cone-beam CT. J Clin Exp Dent. 2018;10(8):e726-31. doi: 10.4317/jced.54310

» https://doi.org/10.4317/jced.54310

37- Abat VH, Keser G, Yülek H, Gencoglu N, Namdar Pekiner F. Assessment of marginal bone loss, distal caries, and external root resorption in second molars adjacent to impacted third molars: a retrospective CBCT and panoramic study. BMC Oral Health. 2025;26(1):128. doi: 10.1186/s12903-025-07527-5

» https://doi.org/10.1186/s12903-025-07527-5

38- Liu Y, Zhou Y, He J, Wei Z, Li Y, Zhou L. Age-related prevalence and correlation of dental and periodontal lesions in second molars adjacent to mesioangular and horizontally impacted mandibular third molars: a CBCT study. BMC Oral Health. 2025;25(1):1042. doi: 10.1186/s12903-025-06404-5

» https://doi.org/10.1186/s12903-025-06404-5

39- Baeza S, Cáceres N, González G, Guzmán C, Paz Sepúlveda M, Valenzuela I. Caracterización de exodoncia de terceros molares [Characterization of third molar extraction]. Rev Científica Odontológica. 2021;9(3):e075. Spanish. doi: 10.21142/2523-2754-0903-2021-075

» https://doi.org/10.21142/2523-2754-0903-2021-075

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Published

2026-03-30

Issue

Vol. 34 (2026)

Section

Original Articles

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How to Cite

Ge, X., Cui, Y., Li, N., Lv, T., Liang, Y., Wu, H., Gu, Y., Li, M., Liu, C., Guo, Y., & Hu, K. (2026). Influence of impacted mandibular third molars on pathological changes on themselves and adjacent tissues across different age groups: a cross-sectional study. Journal of Applied Oral Science, 34, e20250677. https://doi.org/10.1590/1678-7765-2025-0677