Role of Marginal Ridge Shape and Contact Extent in Proximal Caries Between Primary Molars

Objectives: To determine different combinations of marginal ridge shape (MRS) and contact extents in nature of the contact between primary molars and its correlation with the presence of carious lesions on radiographic examination of approximal surfaces. Study design: Retrospective study of 347 clinical records, including photographs and bitewing radiographs, were assessed for intact MRS and caries extent. The carious lesions were scored (0–5, Mejàre scoring system) radiographically and correlated to the intact MRS on clinical photographs, and strength of associations quantified using logistic regression analysis and chi-square tests. Results: Primary molars, 848(contact extent), and 757(MRS) were analyzed. Combination of straight-convex(35.4%) MRS was more common (p<0.001). None of the approximal surfaces were caries-free for straight and straight MRS with 36.4% of both approximal surfaces exhibiting caries in enamel, and 38.2% of one approximal surface exhibiting caries in dentin. Approximately 90% of the primary molars with substantial contacts exhibited carious lesions in the enamel and 80% with light contacts exhibited carious lesions in the dentin (p<0.001). Conclusion: Six different combinations of intact MRS were identified. Combination of concave-convex shapes exhibited caries extending into dentin. Substantial and/or light contacts between primary molars showed higher caries experience in the approximal surfaces.

Marginal ridge; Primary molars; Approximal caries; Interproximal caries

1. Dean J, Barton D, Vahedi I, Hatcher E. Progression of Interproximal Caries in the Primary Dentition. J Clin Pediatr Dent;22:59-62. 1997.

2. Mejàre I, Källestål C, Stenlund H. Incidence and Progression of Approximal Caries from 11 to 22 Years of Age in Sweden: A Prospective Radiographic Study. Caries Res;33:93-100. 1999.

3. McDonald RE, Avery DR. Dentistry for the Child and Adolescent. Mosby Incorporated. 2004.

4. Carlsen O. Dental morphology. Munksgaard, Copenhagen. 1987.

5. Allison PJ, Schwartz S. Interproximal Contact Points and Proximal Caries in Posterior Primary Teeth. Pediatr Dent;25:334-340. 2003.

6. Sun K.T., Li YF, Hsu JT, Tu MG, Hung CJ, Hsueh YH, Tsai HH. Prevalence of Primate and Interdental Spaces for Primary Dentition in 3- to 6-Year-Old Children in Taiwan. J Formos Med Assoc;117:598-604. 2018.

7. Warren J, Slayton R, Yonezu T, Kanellis M, Levy S. Interdental spacing and caries in the primary dentition. Pediatr Dent;25:109-13. 2003.

8. Almer Nielsen L, Madsen DB. Selektiv brug af bitewing-undersøgelse til diagnostik af approksimal caries i primære molarer. Tandlægebladet; 109:370-374. 2005.

9. Cortes A, Martignon S, Qvist V, Ekstrand K. Approximal Morphology as Predictor of Approximal Caries in Primary Molar Teeth. Clin Oral Invest;22:951-959. 2018.

10. Kirthiga M, Muthu M, Kayalvizhi G, Krithika C. Proposed Classification for Interproximal Contacts of Primary Molars Using Cbct: A Pilot Study. Wellcome open research;3. 2018

11. Muthu M, Kirthiga M, Kayalvizhi G, Mathur V. OXIS Classification of Interproximal Contacts of Primary Molars and Its Prevalence in Three- to Four-Year-Olds. Pediatr Dent;42:197-2. 2020.

12. Kirthiga M, Muthu M, Lee J, Kayalvizhi G., Mathur P, Song J, Rajesh P. Prevalence and correlation of OXIS contacts using Cone Beam Computed Tomography (CBCT) images and photographs. Int J Paed Dent;00:1–8. 2020.