Proposed classification for interproximal contacts of primary molars using CBCT: a pilot study

Abstract

Background: Interproximal contact areas in primary teeth are known to be broader, flatter, and situated more gingivally than in permanent teeth. The objective of the present study was to evaluate the different types of intact interproximal contact areas in primary teeth using cone beam computed tomography (CBCT) among children. Methods: A cross-sectional study was designed with 74 contacts from 28 existing CBCT images of children aged between 3 and 14 years, obtained from the Indian Dental Education Academy, Chennai, India. The shape of the contact area was observed at three levels, the coronal, middle, and apical thirds, in three different sections of CBCT. Prevalence of the types of contact areas was expressed in the form of numbers and percentages. Results: The weighted Cohen’s kappa values for inter-examiner reliability was 0.893 at baseline. Results exhibited four different types of contact areas between the primary molars, namely, O type, X type, I type, and S type, based on the shapes observed; hence, the proposed classification is referred to as OXIS. The most common pattern seen was I (66.2%), followed by X (21.6%), O (9.4%) and the least common was S (2.7%). Conclusion: The three-dimensional evaluation of intact interproximal contact areas between primary molars are of four types, O,X, I and S.

OXIS contact areas of primary molars – a two center cross-sectional study

“…The percentage of ‘S’ contacts observed was 5.5% in Center 1 in contrast to 17.0% in Center 2. This result differed from those found in the previous studies 9 – 11 .…”

“…The percentage of ‘O’-type contacts was 19% in Center 1 in contrast to 6% in Center 2. The result observed in Center 2 was similar to that reported in a previous study 10 , but differed from other studies 9 , 11 . The present study also showed more type ‘O’ contacts in the maxilla than in the mandible in both centers.…”

“…One of the main limitations of the clinical study conducted in Puducherry was that the OXIS contacts could not be generalized to other ethnic populations and needed to be confirmed in future studies 10 . Although the presence of OXIS was established in previous studies, there were statistically significant differences in the prevalence of individual contact types among those studies 9 – 11 . Therefore, the aim of the present study was to investigate the prevalence of OXIS contact areas of primary molars in study models of children aged between three and six years in two different ethnic populations.…”

“…To match the sample from Center 1, 200 samples were chosen from the 4,476 available models from a previous study 10 in Center 2. The sample size evaluated in the previous studies included 74 contacts 9 , 1,343 contacts 11 , and 4,476 contacts 10 in the epidemiological study. The age distribution chosen in the present study was 3–6 years in the first Center, with the majority of children (87%) aged between three and five years.…”

“…In this study, the morphology of the interproximal surfaces between the distal surfaces of the first molar and the mesial surfaces of the second molar was scored as four variants: concave-concave, concave-convex, convex-concave, and convex-convex. However, the specific types of contact areas between primary molars were first established in 2018 as O (open contact), X (point contact), I (straight contact), and S (curved contact) types, and the OXIS classification was proposed 9 . This was later confirmed in a population-based study of 1,119 schoolchildren aged 3–4 years 10 .…”