Interproximal Contact Research Articles

Relationship between pre-treatment orthodontic case complexities and their treatment outcomes

PurposeTo determine whether pre-treatment orthodontic case complexities were associated with their treatment outcomes in each category of malocclusion. Materials and methodsTwo hundred orthodontic cases treated with edgewise appliances from university clinic that satisfied requirements for the certification were studied. The Discrepancy Index (DI) and the Objective Grading System (OGS) were calculated. The relationship between these measurements was evaluated using Pearson’s correlation coefficient. ResultsThe mean DI score was 23.67 ± 10.30, and the mean OGS score was 19.92 ± 6.92. Statistically, there was only a weak and insignificant correlation between the DI and OGS (r = 0.055, p > 0.05). Buccolingual inclinations and interproximal contacts were components that had the highest and lowest mean OGS scores respectively. ConclusionMalocclusion complexity was not associated with orthodontic treatment outcomes. Cases which underwent two-phase treatment were found to have the most complex pre-treatment malocclusion and also the most unsatisfactory clinical outcomes. The OGS component with the highest discrepancies was buccolingual inclinations.

Effect of the interproximal contact level on the perception of smile esthetics.

Many dental and facial components affect smile esthetics, and dental professionals' opinions regarding dental esthetics may not always coincide with the perceptions and expectations of the patients. This work is designed to determine the dimensions of the interproximal contact areas that are considered the most or least attractive according to a group of laypersons, dentists and technicians. Two photographs of female and male smiles showing a full smile were taken with a Nikon® camera and digitally altered using Adobe® Photoshop. The length of the interproximal contact areas was altered to generate 2 sets of images (3 images of the female and 3 images of the male smile in each set). A group of 40 laypersons, 40 dentists and 40 dental technicians were asked to select the most and the least attractive image in each set. An interproximal contact ratio of 50:40:30 [%] was the most attractive arrangement (40.00% and 38.33% for the female and male smiles, respectively). The 'reversed' ratio of 30:40:50 [%] was the least attractive to the participants (57.50% and 44.17% for the female and male smiles, respectively). There were differences in the rankings of the most and the least attractive smiles among the 3 groups of evaluators. The 'ideal' interproximal contact ratio of 50:40:30 [%] is perceived to be the most attractive. However, the smile esthetics perception among dental professionals is not always in agreement with the perception of laypersons.

Intrasubject comparison of digital vs. conventional workflow for screw-retained single-implant crowns: Prosthodontic and patient-centered outcomes.

The aim of this intrasubject clinical study was to measure and compare prosthodontic and patient-reported outcome measures (PROMs) in the fabrication of implant-supported, all-ceramic single crowns with a full digital workflow and a conventional workflow. Thirty-one patients were subjected to first a digital (test group) and then a conventional impression (control group) at the same visit. From the intraoral optical scanner (IOS), a screw-retained, monolithic crown was delivered according to a complete digital workflow (no cast), whereas a veneered crown on a zirconia (Zi) frame was provided as a control treatment. Both crowns were assessed during the clinical stages of try-in. Prosthodontic outcomes (contact points, occlusion, PROMs, and esthetic results using the white esthetic score [WES]) were assessed. Occlusion and interproximal contacts showed comparable results for the two workflows (p=0.37 and p=0.36, respectively), whereas the global WES was significantly higher (p<0.0001) in the control group. Patient satisfaction scores, using visual analog scales (VAS), were significantly better for IOS than for conventional impressions (p=0.0098). On the contrary, patients' perception of the esthetic outcomes showed significantly higher value (p<0.0001) in the control group. Both workflows allowed the delivery of ceramic crowns within two appointments. The clinical fit was acceptable in both groups. A better esthetic outcome, in both patients' and clinicians' opinions, was found in the control group. PROMs showed higher satisfaction with the IOS.

The accuracy of clinician evaluation of interproximal contacts using different methods

Statement of problemComplete seating of a single crown may not be possible if the interproximal contacts are excessively tight. Incomplete seating can lead to open margins, inflammation of the gingival tissue, and recurrent dental caries. PurposeThe purpose of this in vitro study was to determine the accuracy of 3 different methods of evaluating interproximal contacts when seating a single crown. Material and methodsThirty-five restorative dentists practicing in the Lincoln, Nebraska, area were polled to determine the methods they used most commonly to evaluate the interproximal contacts of crowns. These dentists then evaluated the interproximal contacts of 9 anatomic contour zirconia crowns on a dentoform using 3 different methods: floss and explorer, occlusal articulating film (AccuFilm), and shim stock. Crown fit was evaluated using 1 method at a time. Each crown was recorded as either “accept” or “reject” according to the individual clinician. All data were analyzed with the McNemar test (α=.05). ResultsOf the 35 restorative dentists polled, 34 identified floss and explorer, 9 identified occlusal articulating film, 3 identified shim stock, and 3 identified an occlusal spray as their method of evaluating interproximal contacts. These methods were used either alone or in conjunction with other methods. Evaluation of the in vitro data revealed that shim stock and occlusal articulating film were significantly more accurate than floss and explorer for assessing interproximal contacts in poorly fitting crowns (P<.001). For well-fitting crowns, shim stock and occlusal articulating film were significantly more accurate than floss and explorer (P<.001). ConclusionsThis study showed that the floss and explorer method was the least accurate means of evaluating the interproximal fit of crowns. Shim stock provided the most accurate method of evaluating interproximal contact, and occlusal articulating film provided both high accuracy and a visible mark to facilitate adjustment.

Black triangles: Preventing their occurrence, managing them when prevention is not practical

The interdental papilla is very important for an aesthetic smile. Black triangles are defined as the embrasures cervical to the interproximal contact that are not filled by gingival tissue. These spaces are the most negatively ranked gingival factor by laypeople. Management of black triangles requires high quality diagnosis and a multidisciplinary approach must be considered mandatory to achieve a successful clinical outcome. Much of what is applicable is born from severely complicated periodontal regeneration and implant therapy. This review covers the multifactorial etiology and the management of black triangles.

Randomized Prospective Clinical Trial of Class II Restorations Using Low-shrinkage Flowable Resin Composite.

The aim of this prospective, randomized, split-mouth clinical trial was to evaluate postoperative sensitivity, clinical performance, and interproximal contacts after using different restorative systems. Fifty-three subjects each received three class II restorations according to the restorative systems: conventional resin composite (PA: Peak Universal+Amelogen Plus, Ultradent), low-shrinkage flowable and nanoparticulate resin composites (ABF: Adper Single Bond 2+Filtek Bulk Fill Flow+Filtek Z350XT, 3M ESPE), and low-shrinkage flowable and microhybrid resin composites (XST: XP Bond+SDR+TPH3, Dentsply). Postoperative sensitivity was assessed at 24 hours, seven days, 90 days, and six months. The clinical performance and interproximal contacts were evaluated at baseline, six months, and one year. Friedman, Wilcoxon, Kruskal-Wallis, and Mann-Whitney tests were used to evaluate postoperative sensitivity and interproximal contacts. The equality test of two proportions and logistic regression analysis were used to assess the clinical performance. No statistically significant differences were observed among groups for postoperative sensitivity. The highest spontaneous sensitivity was reported at 24 hours. ABF was the only group that did not present a reduction in cold sensitivity. Color, marginal discoloration, and superficial staining showed differences among the groups. XST did not show superficial staining after one year. No differences were observed among groups in relation to interproximal contacts. XST resulted in the loss of interproximal contact after one year. Different types of restorative systems do not influence postoperative sensitivity; however, ABF maintained cold sensitivity over time. Marginal discoloration occurred for all groups but occurred earliest for PA. XST presented a reduction of interproximal contact after one year of evaluation.

Closing open contacts adjacent to an implant-supported restoration

Loss of interproximal contact between fixed implant-supported restorations and the adjacent teeth is one of the most common complications in implant dentistry. This article presents a clinical chairside technique for closing open contacts adjacent to an implant-supported restoration. A silicon model is perfused from a restoration-level impression using the open tray technique. Composite resin is bonded to the implant-supported ceramic restoration extraorally to restore the interproximal contact. The tooth and restoration contact is double confirmed on the silicon model and in the mouth. This chairside procedure may save time and improve patient comfort.

Interproximal contact loss in a retrospective cross-sectional study of 4325 implants: Distribution and incidence and the effect on bone loss and peri-implant soft tissue

Statement of problemInterproximal contact loss (ICL) is a common finding between implant restorations and teeth, yet few reports have been published on incidence or related complications. PurposeThe purpose of this cross-sectional retrospective study was to measure the ICL of 4325 implants, including single and multiple splinted restorations. Material and methodsData on 4325 implants were extracted from patient records on ICL, time of follow-up, implant location, and sex of the participant for whom implants were placed in a private practice between 1999 and 2016. Periapical radiographs were used to evaluate the crestal bone level (CBL), whereas peri-implant soft tissues were evaluated with the implant mucosal index (IMI). Measurements (ICL, IMI, and CBL) were evaluated with an average follow-up of 4.5 years (range: 0.25 to 21 years). ICL was assessed in relation to the implant location and sex and grouped by the last clinical recall (1, 2-3, 4-5, 6-7, or 8+ years) to evaluate the effect of time. Data were analyzed by the chi-square test (α=.05). ResultsOverall, 17% of implants had ICL, and this significantly increased over time from 11% at 1 year to 29% at ≥8 years (chi-square: 123.8, P<.001). Mandibular implants had more ICL (20%) than maxillary implants (15%) (chi-square: 17.5, P<.001), whereas no difference was found between molar and premolar sites or male and female participants. There was no significant effect of ICL on CBL over time, but there was an increase in inflammation with higher IMI scores at ICL sites. ConclusionsThe incidence of implant ICL was found to be 17%, and ICL was found to increase over time up to 27% at ≥8 years of follow-up. ICL was more common in posterior and mandibular sites. ICL was shown to increase soft tissue inflammation but was not found to affect implant CBLs.

The contrast of demineralization on tooth occlusal surfaces from 405 to 1950-nm with varying depth.

Near Infrared Reflectance (NIR) is a new imaging technology that detects dental caries (decay) on tooth occlusal surfaces and in the interproximal contact sites between teeth. Conventional techniques, mostly dental x-rays, do not provide the high sensitivity and specificity at the vulnerable pits and fissure regions. The contrast of demineralization on tooth surfaces changes with increasing severity and the magnitude of that change with depth depends on the wavelength. The purpose of this study is to determine how the contrast changes with depth as a function of wavelength. Demineralization of varying depth was produced in 1.5 × 1.5 mm exposed windows after 1, 2, 3, 4, and 5 days of exposure to a demineralizing solution at pH 4.5. Lesions were imaged at 405, 630, 850, 1300, 1460, 1535, 1675, and 1950-nm with multiple imaging systems. The highest lesion contrast was measured at 1950-nm.

Three-dimensional assessment of proximal contact enamel using optical coherence tomography

ObjectiveThe purpose of this study was to detect and investigate the association of enamel microcracks with demineralization at proximal contact areas of premolars, using 3D swept-source optical coherence tomography (SS-OCT). MethodsExtracted maxillary and mandibular premolars (n=50 each), without any visible tooth cracks, were examined for demineralization of interproximal contact areas, using the International Caries Detection and Assessment System (ICDAS). SS-OCT was used to evaluate demineralization and detect microcracks. Demineralization progression was divided into 4 types by depth: 0 for sound enamel and Type I, II, and III for enamel demineralization penetrating into the outer third, the middle third, and the inner third of the enamel thickness, respectively. Enamel microcracks were classified according to the predominant crack pattern: Type O, no cracks; Type A, subsurface microdefects; Type B, enamel microcrack running along the direction of the enamel prism; Type C, enamel microcrack running transverse to the enamel prism direction; and Type D, a combination of patterns A, B, and C. SS-OCT findings were confirmed by confocal laser scanning microscopy observation. ResultsMicrocracks confined within the superficial enamel in proximal contact areas were seen as bright lines on SS-OCT. There were significant positive correlations among ICDAS codes, demineralization levels, and microcrack distribution (p≤0.001). The mesial side of maxillary premolars showed significantly more demineralization (n=36) and microcracks (n=27) than that of the mandibular premolars (n=20 and n=14, respectively; p<0.001). SignificanceThe presence of microcracks within the superficial enamel in proximal contact areas could be determined using SS-OCT, and correlated with the level of demineralization. 3D SS-OCT is a valuable diagnostic tool for comprehensive assessment of microstructural changes related to enamel demineralization and crack development.

A Novel Full-Digital Protocol (SCAN-PLAN-MAKE-DONE®) for the Design and Fabrication of Implant-Supported Monolithic Translucent Zirconia Crowns Cemented on Customized Hybrid Abutments: A Retrospective Clinical Study on 25 Patients.

Purpose: To present a novel, full-digital protocol for the design and fabrication of implant-supported monolithic translucent zirconia crowns cemented on customized hybrid abutments. Methods: The present retrospective clinical study was based on data from patients who had been treated with single Morse-taper connection implants (Exacone®, Leone Implants, Florence, Italy) and were prosthetically restored with monolithic translucent zirconia crowns, cemented on customized hybrid abutments. The full-digital protocol (SCAN-PLAN-MAKE-DONE®) consisted of 8 phases: (1) intraoral scan of the implant position with scanbody; (2) computer-assisted design (CAD) of the individual abutment (saved as “supplementary abutment design” in external folder) and temporary crown; (3) milling of the individual zirconia abutment and of the temporary polymethyl-methacrylate (PMMA) crown, with extraoral cementation of the zirconia abutment on the relative titanium bonding base, to generate an individual hybrid abutment; (4) clinical application of the individual hybrid abutment and cementation of the temporary PMMA crown; (5) two months later, intraoral scan of the individual hybrid abutment in position; (6) CAD of the final crown with margin line design on the previously saved “supplementary abutment design”, superimposed on the second scan of the abutment in position; (7) milling of the final crown in monolithic translucent zirconia, sintering, and characterization; and (8) clinical application of the final crown. All patients were followed for a period of 1 year. The primary outcomes of this study were the marginal adaptation of the final crown (checked clinically and radiographically), the quality of occlusal and interproximal contact points at delivery, and the aesthetic integration; the secondary outcomes were the 1-year survival and success of the implant-supported restoration. An implant-supported restoration was considered successful in the absence of any biological or prosthetic complication, during the entire follow-up period. Results: In total, 25 patients (12 males, 13 females; 26–74 years of age; mean age 51.1 ± 13.3 years) who had been restored with 40 implant-supported monolithic translucent zirconia crowns were included in this study. At delivery, the marginal adaptation was perfect for all crowns. However, there were occlusal issues (2/40 crowns: 5%), interproximal issues (1/40 crowns: 2.5%), and aesthetic issues (1/40 crowns: 2.5%). The overall incidence of issues at delivery was therefore 10% (4/40 crowns). At 1 year, one implant failed; thus the survival of the restorations was 97.5% (39/40 crowns in function). Among the surviving implant-supported restorations, three experienced complications (one loss of connection between the hybrid abutment and the implant, one decementation of the zirconia abutment, and one decementation of the zirconia crown). The success of restorations amounted to 92.4%. Conclusions: The restoration of single Morse-taper connection implants with monolithic translucent zirconia crowns cemented on customized hybrid abutments via the novel SCAN-PLAN-MAKE-DONE® full-digital protocol seems to represent a reliable treatment option. However, further studies on a larger number of patients and dealing with different prosthetic restorations (such as implant-supported fixed partial prostheses) are needed to confirm the validity of this protocol.

The development of new image receptor-holding instruments with appropriate horizontal X-ray beam angulation for periapical radiographs.

This study aimed to develop new image receptor-holding instruments with appropriate horizontal X-ray beam angulation, based on the anatomical data of posterior region interproximal surfaces derived from archived CT images. CT images of 92 patients with sound upper and lower dental arches were collected from our CT database and analyzed to determine the angles between the tangential interproximal contact line and the central groove line of posterior teeth. The average angle for each site was calculated and used to modify instruments using a three-dimensional printer. The utilities of the conventional and the modified instruments for viewing proximal surfaces were compared using two dry skulls. The right and left sides of each site, except for the lower second premolar and first molar sites, did not differ significantly. The difference between the sites was 2.0°; hence, we calculated mean values for the two sides at each site. In the maxilla, the angles of the first and second premolar, second premolar and first molar, and first and second molar to the groove line were 83.9° (±5.4°), 84.4° (±3.9°), 81.6° (±5.1°), while those in the mandible were 85.0° (±9.2°), 85.0° (±4.0°), and 90.6° (±4.9°), respectively. The holding instruments modified to 80° demonstrated better proximal viewing ability in the upper molar region than conventional instruments. The mean angles of the interproximal surfaces were determined from CT data. The image receptor holding-instruments were modified according to these angles to allow appropriate X-ray angulation, which facilitated improved observation of the proximal surfaces of teeth in the posterior region in this pilot in vitro study.

Long term stability of treatment outcome after fixed orthodontic treatment with or without premolar extraction

PurposeTo evaluate and compare the long term stability of treatment outcome in patients treated with fixed orthodontic treatment with and without premolar extractions. Material and methodsFifty five debonded patients (35 females and 20 males) with complete pre-treatment (T0) and post-treatment (T1) records with at least 3 years of post-retention (T2) were included in the study. These patients were divided into two groups; Extraction group comprising of 30 patients who had undergone 4 premolar extractions and non-extraction group had 25 patients. Long term stability of post-treatment occlusion was assessed with Little’s irregularity index, intercanine width and ABO model grading system. ResultsThe incisor irregularity score increased in both extraction and non-extraction groups from post-treatment (T1) to post-retention (T2) and the mean changes were statistically significant. The results of Mann–Whitney test for Little’s irregularity index and intercanine width showed no statistically significant differences between the extraction and the non-extraction groups at T1 to T2. The overall mean changes in the ABO variables showed no statistically significant differences (P>0.05) from post-treatment (T1) to post-retention phase (T2) in extraction and non-extraction groups except interproximal contacts, which showed a statistically significant difference. ConclusionThere was significant relapse in the alignment of maxillary and mandibular anterior teeth with a change in Little’s irregularity score, intercanine width and ABO scores from post-treatment to post-retention. The comparison of relapse in extraction and non-extraction groups did not show significant differences from T1 to T2. Therefore, similar relapse may be expected irrespective of treatment plan.

The use of sectional matrix in direct restoration of a structurally compromised posterior tooth: a clinical technique.

This report describes a clinical technique to facilitate the placement of direct composite resin restorations in structurally compromised posterior teeth, to restore proper anatomical contours and interproximal contacts using sectional matrix kit and thermoplastic impression material.

The effects of different bracket types on orthodontic treatment evaluated with the objective grading system

Background: Standard edgewise and preadjusted Roth are two bracket types widely used for orthodontic treatment. Whether one of these bracket types offers better treatment results than the other requires further evaluation. The Objective Grading System created by the American Board of Orthodontics (ABO) is one of the most reliable indices used to evaluate treatment outcomes. Objectives: To determine the effects of using two different bracket types on treatment outcomes by using the Objective Grading System. Methods: The sample for this study consisted of 64 randomly selected post-treatment dental casts and panoramic radiographs. Of these samples, 32 were treated with a standard edgewise bracket, and the others were treated with a preadjusted Roth bracket. Patient samples were included if they had non-extraction Class I malocclusion (minor crowding 0.05). The highest score was found for the buccolingual inclination parameter, and the lowest score was for interproximal contacts. Conclusion: According to the Objective Grading System, there are no statistically significant differences between the orthodontic treatment outcomes obtained using a standard edgewise or a preadjusted Roth bracket.

Evaluation of adjacent tooth displacement in the posterior implant restoration with proximal contact loss by superimposition of digital models

PURPOSEThis study was conducted to investigate patterns of adjacent tooth displacement in the posterior implant with interproximal contact loss (ICL) by 3-D digital superimposition method.MATERIALS AND METHODSPosterior partially edentulous patients, restored with implant fixed partial prostheses before 2011 and suffered from food impaction of ICL between 2009 and 2011, were included. Two dental casts, at the time of delivery and at the time of food impaction in a same patient, was converted into 3-D digital models through scanning and superimposition was performed to assess chronologic changes of the dentition. Directions of tooth displacement were evaluated and the amount of ICL was calculated. Correlations between the amount of ICL and elapsed time, or between the amount of ICL and age after function, were assessed at a significance level of P<.05.RESULTSA total number of 13 patients (8 males, 5 females) with a mean age of 65.76 ± 9.94 years and 17 areas (4 maxillae, 13 mandibles) were included in this retrospective study. Teeth adjacent to the implant restoration showed complex displacements but characteristic tendency according to the location of the arch. The mean amount of ICL was 0.33 ± 0.14 mm. Elapsed time from function to ICL was 61.47 ± 31.27 months. There were no significant differences between the amount of ICL and elapsed time, or age (P>.05).CONCLUSIONNatural teeth showed various directional movements to result in occlusal change in the arch. The 3-D superimposition of chronologic digital models was a helpful method to analyze the changes of dentition and individual tooth displacement adjacent to implant restoration.

Unconventional implant treatment: Primary teeth as functional provisional restoration

Replacement of hopeless retained primary teeth with dental implants offers various advantages, such as preservation of the crestal bone and elimination of the need to restore the adjacent teeth. Various methods of temporization have been advocated with the aim to support the peri-implant tissues and esthetics; however, longer chairside time is required to accurately reproduce the interproximal contacts and identify the location of the cervical margin. Recently, few case reports utilized a patient's natural teeth as provisional restorations supported by the immediately placed implants or splinted to the adjacent teeth. The case report presented here illustrates the implant placed through the crown of primary teeth in the maxillary and mandibular first molar and utilization of primary teeth as functional provisional restoration. These primary teeth acts as natural space maintainer, maintaining the peri-implant tissues, during the healing period of implant as well as minimize the chairside clinician's time for the fabrication of temporary prosthesis.

Numeric simulation model for long-term orthodontic tooth movement with contact boundary conditions using the finite element method

Introduction Although many attempts have been made to simulate orthodontic tooth movement using the finite element method, most were limited to analyses of the initial displacement in the periodontal ligament and were insufficient to evaluate the effect of orthodontic appliances on long-term tooth movement. Numeric simulation of long-term tooth movement was performed in some studies; however, neither the play between the brackets and archwire nor the interproximal contact forces were considered. The objectives of this study were to simulate long-term orthodontic tooth movement with the edgewise appliance by incorporating those contact conditions into the finite element model and to determine the force system when the space is closed with sliding mechanics. Methods We constructed a 3-dimensional model of maxillary dentition with 0.022-in brackets and 0.019 × 0.025-in archwire. Forces of 100 cN simulating sliding mechanics were applied. The simulation was accomplished on the assumption that bone remodeling correlates with the initial tooth displacement. Results This method could successfully represent the changes in the moment-to-force ratio: the tooth movement pattern during space closure. Conclusions We developed a novel method that could simulate the long-term orthodontic tooth movement and accurately determine the force system in the course of time by incorporating contact boundary conditions into finite element analysis. It was also suggested that friction is progressively increased during space closure in sliding mechanics.

Interproximal Open Contacts Between Implant Restorations and Adjacent Teeth. Prevalence – Causes – Possible Solutions

To present the prevalence and contributing factors of interproximal contact loss (ICL) between implant restorations and adjacent teeth, and to provide recommendations for possible prevention and treatment of this complication. The authors explored the dental literature on PubMed on ICL between implants and adjacent teeth, interproximal contacts, open contacts, teeth migration causes, facial bone formation, and facial bone changes. ICL between fixed implant prostheses and adjacent teeth has been reported. A literature search revealed 7 studies showing a high prevalence of ICL between implant prostheses and adjacent teeth. The literature indicates that this ICL is greater in the mesial aspect in comparison with the distal. As identified by the literature review, ICL in the maxilla ranged between 18% and 66% versus 37% to 54% in the mandible. ICL might occur as early as 3 months after prosthetic treatment. The literature review documented possible tooth migration causes, crown-related causes, and bone formation/growth-related causes of ICL. ICL is a common multifactorial implant complication. The clinical condition will dictate if the implant crown needs to be modified/replaced or the natural tooth needs to be restored to reestablish interproximal contact between an implant prosthesis and adjacent tooth. Periodic evaluations of interproximal contacts between implant restorations and the adjacent teeth and the use of screw-retained restorations due to ease of removal is recommended to diagnose and mitigate the problem. An orthodontic retainer or occlusal guard may help prevent ICL between the implant restoration and the adjacent tooth.

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

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.