Displacement of Cephalometric Points A and B with Changes in Maxillary and Mandibular Incisor Inclination

Abstract

Objectives: This study aimed to evaluate whether treatment-induced changes in maxillary and mandibular incisor inclination are associated with sagittal and vertical displacement of cephalometric points A and B in skeletally mature, non-extraction patients. 

Materials and Methods: Pre- (T0) and post-treatment (T1) lateral cephalograms of 90 skeletally mature patients (45 female, 45 male) were retrospectively analyzed. Inclusion required a complete incisor complement and a minimum 4° change in both UI-SN and IMPA. Tracings were performed with NemoCeph 2025; T0 and T1 films were superimposed on S-N, with a horizontal reference at 7° to S-N and a vertical reference through Sella. Method error was assessed by remeasuring 30 patients four weeks after the initial measurements, and intra-observer reliability was calculated using a two-way mixed-effects, absolute-agreement, single-measurement model. The threshold for statistical significance was set at p < 0.05. 

Results: Linear regression analysis demonstrated that incisor inclination significantly influenced the sagittal positional change of both landmarks. A 1° increase in the UI-SN angle corresponded to approximately 0.043 mm of posterior displacement of point A, while a 1° increase in IMPA was associated with approximately 0.055 mm of posterior displacement of point B. Vertical positional change was not significantly explained by incisor inclination. The association between UI-SN and point A was stronger in males than in females. 

Conclusion: Points A and B are not positionally stable during orthodontic treatment; both undergo sagittal displacement proportional to incisor inclination change, with measurable effects on SNA and SNB.

Keywords

• Anatomic landmarks
• Cephalometry
• Incisor
• Tooth movement techniques

Supporting Institution

Istanbul Okan University

Ethical Statement

Ethical approval for this study was granted by the Ethics Committee of the Institute of Graduate Studies, İstanbul Okan University on 15.09.2025 (Decision No: 28, Date: 15/09/2025).

Thanks

I would like to express my sincere gratitude to my supervisor, Prof. Dr. Zeynep Ahu ACAR, for her unwavering support throughout this study. I also extend my heartfelt thanks to Prof. Dr. Arzu ARI DEMİRKAYA, Prof. Dr. Kerem ARAS, Prof. Dr. A. Nejat ERVERDİ, Dr. Aybüke ENSARİOĞLU, Dr. Dilara KAHRAMAN, Dr. Banu MERT, and Dr. Pınar KARATABAN for their valuable contributions.

Maksiller ve Mandibular Keser Eğimlerindeki Değişikliklere Bağlı Olarak ‘A’ ve ‘B’ Noktalarının Konum Değişiklikleri

Abstract

Amaç: Bu çalışmanın amacı, iskeletsel olarak olgun ve çekimsiz tedavi gören hastalarda maksiller ve mandibular keser eğimindeki tedaviye bağlı değişikliklerin, sefalometrik A ve B noktalarının sagital ve vertikal yöndeki konum değişiklikleri ile ilişkili olup olmadığını değerlendirmektir. 

Gereç ve Yöntemler: İskeletsel olarak olgun 90 hastanın (45 kadın, 45 erkek) tedavi öncesi (T0) ve tedavi sonrası (T1) lateral sefalometrik radyografları retrospektif olarak incelendi. Çalışmaya dahil edilme kriteri olarak keserlerin tam bulunması ve hem UI-SN hem de IMPA değerlerinde en az 4°'lik değişim arandı. Çizimler NemoCeph 2025 yazılımı ile gerçekleştirildi; T0 ve T1 filmleri S-N düzlemi üzerine süperpoze edildi, S-N'ye 7° açıyla yatay referans ve Sella noktasından geçen dikey referans kullanıldı. Ölçüm hatası, 30 hastada dört hafta sonra tekrar ölçüm yapılarak gözlemci içi güvenirlik, iki yönlü karışık etkili, mutlak uyum ve tekli ölçüm modeli kullanılarak hesaplanmıştır. İstatistiksel anlamlılık düzeyi p < 0,05 olarak kabul edilmiştir. 

Bulgular: Doğrusal regresyon analizinde keser eğiminin her iki noktanın sagital konum değişimini anlamlı düzeyde etkilediği görüldü. UI-SN açısındaki 1°'lik artış A noktası için yaklaşık 0.043 mm posterior hareket ile ilişkili bulundu. IMPA açısındaki 1°'lik artış B noktası için yaklaşık 0.055 mm posterior hareket ile ilişkili bulundu. Vertikal yöndeki konum değişimi keser eğimi ile anlamlı düzeyde açıklanamadı. UI-SN ile A noktası arasındaki ilişkinin erkeklerde kadınlara kıyasla daha güçlü olduğu görüldü. 

Sonuç: A ve B noktaları ortodontik tedavi sırasında sabit kalmamakta; her iki nokta da keser eğimindeki değişimle orantılı olarak sagital yönde yer değiştirmekte ve bu durum SNA ile SNB ölçümlerine yansımaktadır.

Keywords

• Anatomik işaretler
• Dişleri hareketlendirme teknikleri
• Kesici diş
• Sefalometri

Supporting Institution

İstanbul Okan Üniversitesi

Ethical Statement

Bu çalışma için etik onay, İstanbul Okan Üniversitesi Lisanüstü Eğitim Enstitüsü Etik Kurulu tarafından 15.09.2025 tarihinde verilmiştir (Karar No: 28, Tarih: 15/09/2025).

Thanks

Bu çalışma boyunca desteğini hiçbir zaman esirgemeyen tez danışmanım Prof. Dr. Zeynep Ahu ACAR'a teşekkür ederim. Ayrıca değerli katkılarından dolayı Prof. Dr. Arzu ARI DEMİRKAYA, Prof. Dr. Kerem ARAS, Prof. Dr. A. Nejat ERVERDİ, Dr. Aybüke ENSARİOĞLU, Dr. Dilara KAHRAMAN, Dr. Banu MERT'e çok teşekkür ederim. Dr. Pınar KARATABAN'a en içten teşekkürlerimi sunarım.

References

1. Hans MG, Palomo JM, Valiathan M. History of imaging in orthodontics from Broadbent to cone-beam computed tomography. Am J Orthod Dentofacial Orthop. 2015;148(6):914–21.
2. Kotuła J, Kuc AE, Lis J, Kawala B, Sarul M. New Sagittal and Vertical Cephalometric Analysis Methods: A Systematic Review. Diagnostics (Basel). 2022;12(7):1723.
3. Downs WB. Variations in facial relationships: their significance in treatment and prognosis. Am J Orthod. 1948;34(10):812–40.
4. Companioni Bachá A, Rodríguez Quiñónez M, Días de Villegas Rushkova V, Otaño Lugo R. Bosquejo histórico de la Cefalometría Radiográfica. Rev Cubana Estomatol. 2008;45(2):54-60.
5. Holdaway RA. Changes in relationship of points A and B during orthodontic treatment. Am J Orthod. 1956;42(3):176–93.
6. Jacobson A. Application of the ‘Wits’ appraisal. Am J Orthod. 1976;70(2):179–89.
7. Hussels W, Nanda RS. Analysis of factors affecting angle ANB. Am J Orthod. 1984;85(5):411–23.
8. Taylor CM. Changes in the relationship of nasion, point A, and point B and the effect upon ANB. Am J Orthod. 1969;56(2):143–63.

9. Bishara SE, Fahl JA, Peterson LC. Longitudinal changes in the ANB angle and Wits appraisal: clinical implications. Am J Orthod. 1983;84(2):133–9.
10. Zamora N, Llamas JM, Cibrian R, Gandia JL, Paredes V. A study on the reproducibility of cephalometric landmarks when undertaking a three-dimensional (3D) cephalometric analysis. Med Oral Patol Oral Cir Bucal. 2012;17(4):e678–88.
11. Grogger P, Sacher C, Weber S, Millesi G, Seemann R. Identification of ‘Point A’ as the prevalent source of error in cephalometric analysis of lateral radiographs. Int J Oral Maxillofac Surg. 2018;47(10):1322–9.
12. Kazandjian S, Kiliaridis S, Mavropoulos A. Validity and reliability of a new edge-based computerized method for identification of cephalometric landmarks. Angle Orthod. 2006;76(4):619–24.
13. Erverdi AN, Sandallı T. A Cephalometric Study of Changes in Point A under the Influence of Upper Incisor Inclinations. Turk J Orthod. 1988;1(1):75-9.
14. Bicakci AA, Cankaya OS, Mertoglu S, Yilmaz N, Altan BK. Does proclination of maxillary incisors really affect the sagittal position of point A? Angle Orthod. 2013;83(6):943–7.
15. Chen Q, Zhang C, Zhou Y. The effects of incisor inclination changes on the position of point A in Class II division 2 malocclusion using threedimensional evaluation: a long-term prospective study. Int J Clin Exp Med. 2014;7(10):3454–60.
16. Al-Nimri KS, Hazza’a AM, Al-Omari RM. Maxillary incisor proclination effect on the position of point A in Class II division 2 malocclusion. Angle Orthod. 2009;79(5):880–4.
17. Krishnamurthy S, Mehta P. Equation between Incisor Inclination Correction and Anteroposterior Movement of Point A to determine the Actual Magnitude of Maxillomandibular Difference. World J Dent. 2017;8(4):300–3.
18. Al-Abdwani R, Moles DR, Noar JH. Change of incisor inclination effects on points a and b. Angle Orthod. 2009;79(3):462–7.
19. Neani H, Mohimd H B, Benyahia H, et al. Impact of incisor repositioning on the cephalometric position of points A and B. Pan Afr Med J. 2022;41:209.
20. Aneesh AM. Evaluation of accuracy and reliability of three different computerized cephalometric programs nemoceph, onyx and facad with conventional hand tracing method. Master thesis. Kulasekaram: Sree Mookambika Institute of Dental Sciences; 2013. Available from: https://api.semanticscholar.org/ CorpusID:55938431
21. Prakash AT, Zoheb M, Priyanka S. Effect of proclination of the upper incisors on Point A in adult Class II division 2 individuals: A cephalometric study. APOS Trends Orthod. 2022;12(2):112-7.
22. Li An T, Cuoghi OA, Mendonça MR de, Bertoz FA. O efeito da retração dos dentes anteriores sobre o ponto A em pacientes submetidos ao tratamento ortodôntico corretivo. Rev Dental Press Ortod Ortop Facial. 2008;13(2):115–23.
23. Hassan S, Shaikh A, Fida M. Effect Of Incisor Inclination Changes On Cephalometric Points A And B. J Ayub Med Coll Abbottabad. 2015;27(2):268–73.
24. Amasyalı M, Sabuncuoğlu FA, Karaçay Ş, Doğru M, Altuğ H. Combined Use of Retraction and Torque Arch with Mini-Screws: A Cephalometric Study. Turk J Orthod. 2018;31(1):1–6.
25. Hong SY, Shin JW, Hong C, et al. Alveolar bone remodeling during maxillary incisor intrusion and retraction. Prog Orthod. 2019;20(1):47.
26. Sun Q, Lu W, Zhang Y, Peng L, Chen S, Han B. Morphological changes of the anterior alveolar bone due to retraction of anterior teeth: a retrospective study. Head Face Med. 2021;17(1):30.
27. Kuc AE, Kotuła J, Nawrocki J, et al. Bone Remodeling of Maxilla after Retraction of Incisors during Orthodontic Treatment with Extraction of Premolars Based on CBCT Study: A Systematic Review. J Clin Med. 2024;13(5):1503.
28. Marques JS, Siqueira VCV de. Estudo das alterações do ponto B durante o tratamento ortodôntico. Rev Dental Press Ortod Ortop Facial. 2007;12(3):136–45.
29. Xu J, Zhou J, Yin Y, Chang L, Chen S. Alveolar bone modeling and bone modeling/ tooth movement ratio during mandibular incisor retraction: a retrospective study [Preprint]. Research Square 2020.
30. Das BR, Jain P, Modi N, Soni P, Datta D, De A. SNA and SNB measurements: A comparative assessment between measurements in conventional 2D cephalogram and 3D conebeam computed tomography-generated values. Int J Oral Care Res. 2021;9(3):71–5.
31. Kalina E, Grzebyta A, Zadurska M. Bone Remodeling during Orthodontic Movement of Lower Incisors-Narrative Review. Int J Environ Res Public Health. 2022;19(22):15002.
32. Chien PC, Parks ET, Eraso F, Hartsfield JK, Roberts WE, Ofner S. Comparison of reliability in anatomical landmark identification using twodimensional digital cephalometrics and threedimensional cone beam computed tomography in vivo. Dentomaxillofac Radiol. 2009;38(5):262–73.
33. Valentim ZL, Capelli Júnior J, Almeida MA, Bailey LJ. Incisor retraction and profile changes in adult patients. Int J Adult Orthodon Orthognath Surg. 1994;9(1):31–6.
34. Patel KS, Kulkarni N, Singh VP, Parikh K. Identification of an Alternate Maxillary Apical Base Landmark from Pre-existing Substitutions. Acta Inform Med. 2014;22(5):347–9.