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Original Research

Open Access

Changes in Andrews' fifth key of occlusion (interproximal contacts) before and after orthodontic treatment

  • Satta Muthu Murugan1,2
  • Vignesh Kailasam3,*,
  • Golla Usha Rao4
  • Chandrasekaran Krithika5
  • Muthusamy Kirthiga1
  • Jagadeesan Aarthi6
  • Aravind Warrier7

1Centre for Early Childhood Caries Research (CECCRe), Department of Pediatric and Preventive Dentistry, Sri Ramachandra Faculty of Dental Sciences, Sri Ramachandra Institute of Higher Education and Research, 600116 Chennai, India

2Centre of Medical and Bio-Allied Health Sciences Research, Ajman University, P.O Box 346, Ajman, United Arab Emirates

3Department of Orthodontics and Dentofacial Orthopedics, Faculty of Dental Sciences, Sri Ramachandra Institute of Higher Education and Research, 600116 Chennai, India

4Department of Orthodontics and Dentofacial Orthopedics, Tamil Nadu Government Dental College, 600001 Chennai, India

5Oral Medicine and Radiology, Meenakshi Academy of Higher Education and Research, 600078 Chennai, India

6Department of Paediatric and Preventive Dentistry, Madha Dental College, 600069 Chennai, India

7Department of Oral Medicine and Radiology, Faculty of Dental Sciences, Sri Ramachandra Institute of Higher Education and Research, 600116 Chennai, India

DOI: 10.22514/jocpd.2024.082 Vol.48,Issue 4,July 2024 pp.86-98

Submitted: 01 December 2023 Accepted: 04 January 2024

Published: 03 July 2024

*Corresponding Author(s): Vignesh Kailasam E-mail:


This study aimed to assess the changes in interproximal contacts before and after orthodontic treatment using the OXIS classification. OXIS refers to the types of contacts that is open (O), point contact (X), straight contact (I), and curved contact (S), and thus the acronym “OXIS”. Interproximal contact data of 30 orthodontic patients were obtained at three time points: T0, at the beginning of treatment; T1, at the end of fixed appliance treatment; and T2, one-year post-treatment. For the maxillary second molar–first molar contact, the most common contact at T0, was the “S” pattern (41.6%) which increased to 61.6% at T1 and reduced to 48.3% at T2. For the maxillary first molar–second premolar contact, maxillary second premolar–first premolar contact, and maxillary first premolar–canine contact, the most common contact at T0 was the “I” pattern (58.3%, 46.5% and 43.3%, respectively), which increased to 88.3%, 93.3%and 73.3%, respectively at T1 and decreased to 80%, 88.3% and 71.6%, respectively at T2. For the maxillary canine–lateral incisor contact and lateral–central incisor contact, the most common contact at T0 was the “O” pattern (45% and 33.3%) while it was the “X” pattern at T1 (63.3% and 80%) and T2 (58.3% and 80%). A similar observation was made for the posterior mandibular and anterior teeth. There was statistical significance for most of the changes in the mandibular contacts (p ˂ 0.05). Interproximal contacts change significantly from T0 to T1. Broader contacts were normal at T1 and T2 in the posterior segments. At T2, changes in the interproximal contacts were observed in the posterior segments, and substantial evidence was available, particularly for the mandibular arch.


Andrews’ fifth key; OXIS; Malocclusion; Inter proximal contacts

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Satta Muthu Murugan,Vignesh Kailasam,Golla Usha Rao,Chandrasekaran Krithika,Muthusamy Kirthiga,Jagadeesan Aarthi,Aravind Warrier. Changes in Andrews' fifth key of occlusion (interproximal contacts) before and after orthodontic treatment. Journal of Clinical Pediatric Dentistry. 2024. 48(4);86-98.


[1] Little RM, Riedel RA, Artun J. An evaluation of changes in mandibular anterior alignment from 10 to 20 years postretention. American Journal of Orthodontics and Dentofacial Orthopedics. 1988; 93: 423–428.

[2] Al Yami EA, Kuijpers-Jagtman AM, van’t Hof MA. Stability of orthodontic treatment outcome: follow-up until 10 years postretention. American Journal of Orthodontics and Dentofacial Orthopedics. 1999; 115: 300–304.

[3] Thilander B. Biological basis for orthodontic relapse. Seminars in Orthodontics. 2000; 6: 195–205.

[4] Andrews LF. The six keys to normal occlusion. American Journal of Orthodontics. 1972; 62: 296–309.

[5] Wheeler RC. An atlas of tooth form. 4th edn. Philadelphia: W. B. Saunders Company. 1969.

[6] Jernberg GR, Bakdash MB, Keenan KM. Relationship between proximal tooth open contacts and periodontal disease. Journal of Periodontology. 1983; 54: 529–533.

[7] Stappert CF, Tarnow DP, Chu SJ. Proximal contact areas of the maxillary anterior dentition. International Journal of Periodontics & Restorative Dentistry. 2000; 30: 471–477.

[8] Strang RH. Class II, division 2 malocclusion. The Angle Orthodontist. 1958; 28: 210–204.

[9] Allison PJ, Schwartz S. Interproximal contact points and proximal caries in posterior primary teeth. Pediatric Dentistry. 2003; 25: 334–340.

[10] Cortes A, Martignon S, Qvist V, Ekstrand KR. Approximal morphology as predictor of approximal caries in primary molar teeth. Clinical Oral Investigations. 2018; 22: 951–959.

[11] Cho VY, King NM, Anthonappa RP. Role of marginal ridge shape and contact extent in proximal caries between primary molars. Journal of Clinical Pediatric Dentistry. 2021; 45: 98–103.

[12] Muthu MS, Kirthiga M, Kayalvizhi G, Mathur VP. OXIS classification of interproximal contacts of primary molars and its prevalence in three- to four-year-olds. Pediatric Dentistry. 2020; 42: 197–202.

[13] Aarthi J, Muthu MS, Kirthiga M, Kailasam V. Modified OXIS classification for primary canines. Wellcome Open Research. 2022; 7: 130.

[14] Kailasam V, Muthu MS, Rao U, Krithika C, Kirthiga M, Arthi J, et al. Prevalence of different types of interproximal contacts in the permanent dentition—a study cast evaluation Wellcome Open Research. 2023. Available at: (Accessed: 11 November 2023).

[15] Littlewood S, Kandasamy S, Huang G. Retention and relapse in clinical practice. Australian Dental Journal. 2017; 62: 51–57.

[16] Kumari S, Sharma A, Sharma K, Singh C. OXIS contact area variations in primary molars among three to five year aged preschool children. European Chemical Bulletin. 2023; 12: 2321–2331.

[17] Kirthiga M, Muthu MS, Kayalvizhi G, Mathur VP, Jayakumar N, Praveen R. OXIS contacts and approximal caries in preschool children: a prospective cohort study. Caries Research. 2023; 57: 133–140.

[18] Başçiftçi FA, Uysal T, Sari Z, Inan O. Occlusal contacts with different retention procedures in 1-year follow-up period. American Journal of Orthodontics and Dentofacial Orthopedics. 2007; 131: 357–362.

[19] Sari Z, Uysal T, Basciftci FA, Inan O. Occlusal contact change with removable and bonded retainers in a 1 year retention period. The Angle Orthodontist. 2009; 79: 867–872.

[20] Reitan K. Clinical and histologic observations on tooth movement during and after orthodontic treatment. American Journal of Orthodontics. 1967; 53: 721–745.

[21] Jeyasree RM, Muthuraj T. An insight into classification, diagnosis and comprehensive management of food impaction. In Sridharan G (eds.). Periodontology-New Insights [Internet]. IntechOpen: London. 2023.

[22] Campos JDFA, Campos MJDS, Caetano PL, Kuchenbecker Rösing C, Farinazzo Vitral RW. The absence of proximal contact point on periodontal parameters of teeth moved into extraction sites. Brazilian Dental Journal. 2022; 33: 74–81.

[23] Patil P. Proximal contact loss: an emerging frequent implant complication. International Journal of Prosthodontics and Restorative Dentistry. 2023; 12: 160–161.

[24] Bompolaki D, Edmondson SA, Katancik JA. Interproximal contact loss between implant-supported restorations and adjacent natural teeth: a retrospective cross-sectional study of 83 restorations with an up to 10-year follow-up. the Journal of Prosthetic Dentistry. 2022; 127: 418–424.

[25] Latimer JM, Gharpure AS, Kahng HJ, Aljofi FE, Daubert DM. Interproximal open contacts between implant restorations and adjacent natural teeth as a risk-indicator for peri‐implant disease—a cross‐sectional study. Clinical Oral Implants Research. 2021; 32: 598–607.

[26] Kailasam V, Rangarajan H, Easwaran HN, Muthu MS. Proximal enamel thickness of the permanent teeth: a systematic review and meta-analysis. American Journal of Orthodontics and Dentofacial Orthopedics. 2021; 160: 793–804.e3.

[27] Manicone P, De Angelis P, Papetti L, Rella E, De Angelis S, D’Addona A. Analysis of proximal contact loss between implant restorations and adjacent teeth: a 10-year retrospective study. International Journal of Periodontics & Restorative Dentistry. 2022; 42: 113–119.

[28] Ramina F, Cremonini F, Pellitteri F, Cavazza M, Lombardo L. Marginal ridge alignment and interproximal bone levels: Evaluation of a possible correlation. APOS Trends in Orthodontics. 2023; 13: 153–160.

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