Quad Matrix System: Leapfrog Technique for Sequential Class II Restorations

Daichi Hayashi

Table of Contents

Introduction

The restoration of Class II cavities with composite resin is one of the most commonly performed basic procedures in restorative treatment, yet it requires a high skill level of the operator and delicate manipulation to be successful. In particular, the accurate reproduction of the anatomical morphology of the adjacent surfaces is essential in the prevention of long-term complications such as secondary caries and gingivitis. 

 Essentially, the ideal adjacent surface restoration requires three clinical requirements 

(i) Tight closure of the gingival embrasure, 

(ii) reproduction of the contact point with appropriate separation between the teeth, 

(iii) the formation of a natural contour of the crown on the buccolingual side. 

 It has been difficult to achieve all of these in a high quality dimension with conventional matrix systems, but Garrison's ‘Quad Matrix system’ is a revolutionary product that incorporates design concepts that precisely achieve these requirements. 

 In this case study, the high clinical performance of the Quad Matrix system and practical solutions to the pitfalls of Class II restorations that operators often face are presented through a series of cases of premolar distal caries. 

Case Outline

The patient, a 22-year-old female, presented to the clinic with a chief complaint of food impaction in the left upper premolar region. 

There were caries in the distal portions of the upper left first and second premolars, each of which was to be restored with composite resin. 

The Quad Matrix system was planned to be applied to each caries. 

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Figure 1. Caries present in the distal centers of the upper left first and second premolars. 

 		Figure 2.The caries was observed when the marginal ridge was explored. In this case, it was decided to remove the caries at first to avoid tearing the rubber dam sheet by the roughened area of the contact. 
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Figure 3. After removal of the caries and preparation of the margin, the rubber dam was applied. The caries was not localized to the adjacent surface and was formed slightly closer to the corner. Figure 4. Selective etching, priming and bonding procedures were performed with FXH100 (Premolars) in place and each adjacent protected. Kurarey K-Etchant syringes and Megabond 2 were applied. 
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Figure 5. QBL (Small) wedges were inserted and retainers were fitted. The retainer has an attachment direction, with the arrow pointing towards the end of the wedge, which opens up the tip of the wedge and provides a tighter closure of the gingival embrasure. The Matrix Band is also wide and covers the corners, making it adaptable to a variety of cavity ranges. In this case, too, the cavity extends close to the corner on the palatal side, but it is adequately covered and can be filled with confidence. In this case, the second premolar was filled first, as it was necessary to ensure that each tooth was filled one at a time while maintaining a clear field of vision during filling. 
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Figure 6. Perfectly sealed to the lowest part. Figure 7. Filling with Kurarey Clearfill Majesty ES Flow. 
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Figure 8. The first premolar was also placed in the same retainer and was found to be perfectly sealed up to the lowest end. Figure 9. This tooth was also filled with Kurarey's Clearfill Majesty ES Flow. To reproduce the fine ridges, they were placed on the subocclusal head with a fine tip for accentuation. 
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Figure 10. Final curing with Kurarey Oxyguard 2 under oxygen barrier. 

 		Figure 11. After occlusal adjustment and polishing. The natural buccopalatal curve and ideal contact were achieved. The band is very thin (0.0016") and the retainer provides an automatic close contact after filling due to the interdental separation. 

Conclusion

The three key points - gingival embrasure, contact point and contour - are requirements that must be fulfilled in Class 2 composite resin fillings. And this is fulfilled by the Quad Matrix system. 

In particular, the unique wedge and its supporting retainer eliminate all of the operator's concerns as soon as the placement is complete. 

It is an excellent system for simple and effective filling of even complex Class 2 cavities in a short time. 

About the Author

Daichi Hayashi Headshot

Daichi Hayashi

Dr. Daichi Hayashi is a practicing dentist and clinical instructor with a strong background in oral surgery and academic research. He currently serves as a clinician and instructor at Apple Dental Clinic, Medical Corporation, where he has been in practice since 2018. Prior to this role, Dr. Hayashi trained in the Department of Oral Surgery at Hyogo Prefectural Awaji Medical Center (2017–2018), gaining valuable experience in advanced surgical care.
 
Dr. Hayashi earned his Doctor of Dental Surgery degree from Okayama University Faculty of Dentistry (2010–2017). His academic interests include circadian biology and its implications for oral and systemic health. He has published research in the Journal of Endocrinology on the role of melatonin in cartilage and its impact on rhythmic gene expression (2019).
 
He is an active member of the Society of Japan Clinical Dentistry and The Academy of Clinical Dentistry, through which he contributes to advancing clinical excellence and dental education in Japan.