Comparative Evaluation of Proximal Contact Tightness in Class II Composite Resin Restoration Using Two Different Matrices: An In-Vivo Study

Maintaining proximal contact in dentition is a fundamental aspect of restorative dentistry that significantly influences oral health and longevity of dental restorations. Proximal contact refers to the relationship between adjacent teeth at their interproximal surfaces, playing a critical role in preventing food impaction, ensuring proper alignment, and supporting periodontal health. Failure to obtain tight proximal contacts can cause food impaction, resulting in caries or periodontal disease and possible movement of teeth. Therefore, effective management of these contacts is essential for aesthetic reasons and the functional stability of dental restorations. When restoring the proximal contact, the reconstruction of correct anatomical contour as well as the provision of appropriate proximal contact tightness is essential for periodontal health.

Research work by Osborn and Dörfer et al,1961 laid the groundwork for understanding the importance of interproximal relationships in restorative dentistry and highlighted the need for precision during the restoration process. Their studies provided insights into the relationships between restoration materials, techniques, and the effectiveness of achieving optimal proximal contacts. They found that factors such as the type of material used, placement techniques, and the design of the restoration significantly influenced the quality of proximal contacts. To achieve proper proximal contact in direct composite resin restorations, the clinical procedure must compensate for the thickness of the matrix as well as the polymerization shrinkage of the composite resin. Both proximal contact tightness, PCT and proximal contours are two key factors that are related to the establishment of proximal surface. The PCT is regarded to be of a dynamic nature that could be influenced by the type, location and size   of the tooth, the position of the patient on the dental chair being supine or upright, the degree of the mouth opening, accessibility to the region, restorative techniques, and the masticatory forces. At different times in one day, PCT has been shown to differ with the periodontal ligament’s fatigue and alterations in viscoelastic characteristics owing to the potential role of circadian rhythms. For placement of the composite resin, varied measures have already been made to sustain the anatomical structure of proximal contact area. Special instruments were utilized to achieve the optimal proximal contour such as diverse matrix systems, separation rings and wedges. There are many different types of matrix systems in the market specifically designed to be utilized with composite resin.

To check PCT in this study, one of the methods used is a digital force gauge.The system used a 0.05-mm-thick metal strip inserted interdentally from an occlusal direction. The metal strip was connected to the digital force gauge. The tightness of the proximal contact was quantified as the maximum frictional force when the strip was slowly removed in a buccal-lingual direction. The maximum force was recorded on the screen of the gauge for each measurement when the gauge was switched to peak mode and the tightness was measured.

The second method used for evaluation of PCT is by passing waxed floss between two teeth, but it is difficult to detect the proximal contact tightness by this method because this is a very subjective method rather than qualitative. The scoring criteria given by Dörfer et al(2001) is commonly used. Score 1 Open contact,when there is visible space between the two teeth. Score 2 is known as  Optimum contact, when passing the floss requires some amount of pressure to pass through. Score 3 is tight contact: when the floss requires maximum pressure and does not pass through easily.  The third method of evaluation is by radiograph analysis by observing presence of gaps or not.