Comparative clinical evaluation of flexible crowns and strip crowns in primary anterior teeth: a 12-month randomized trial

Early childhood caries (ECC) is a chronic multifactorial disorder which continues to be dominant in children, especially in families of low socioeconomic status. Early childhood caries is defined as the existence of one or more tooth decays (non-cavitated or cavitated lesions), missing (due to caries), or filled tooth surfaces in any primary dentition of children under the age of six years. Severe early childhood caries (S-ECC) is a progressive carious form in children, categorized in accordance to the number of affected teeth and the age of patient. Providing care to children who are considered to be at risk from ECC, can be achieved by a specialist who received adequate training and has experience in treating children as well as disease process.

Primary incisors with large or multi-surface caries can be restored with resin composite strip crowns if there is sufficient tooth structure after removing all carious tissues. When remaining tooth structure is minimal and not enough for bonding, pre-veneered aesthetic crowns is a favorable solution. Stainless steel crowns with cosmetic facing have good aesthetics and good retention even with minimal remaining tooth structure. Moisture and hemorrhage control are not critical with these restorations which need minimal chair time and offer full coverage and protection. The findings indicate that stainless steel crowns (SSCs) are valued for durability and cost-effectiveness, but they may cause hypersensitivity. Resin composite strip crowns are used for the rehabilitation of the primary anterior teeth using the celluloid forms of the crowns and resin composite. For many years, Strip crowns had been considered as the most aesthetic option for the mutilated primary anterior teeth. But strip crowns are highly technique sensitive, which require proper moisture control during bonding and the placement of the crowns. This isolation is difficult to obtain in children oral cavity not only due to fewer technique and materials are available for isolation in children but also because children who require these belong to the younger age group and most difficult to manage in operatory.

As an alternative to all these crowns, a new prefabricated aesthetic flexible crowns, made up of hybrid polymer resin and which is Bis -GMA free and metal free high strength resin polymer has been introduced as Bioflx crowns. According to the manufacturers, they can withstand high compressive forces, and are highly durable. These flexible crowns allow the paediatric dental practitioner to provide aesthetics of new age crowns with easy manipulation, conservative preparation similar to stainless steel crowns. However, no clinical studies have yet been published looking at the clinical performance of these Bioflx crowns in the anterior region.

Thus, the main purpose of this prospective, randomized clinical study is to compare the clinical efficacy of aesthetic flexible composite crown (Bioflx crowns) with a commercially available anterior composite strip crowns. The null hypothesis is that there is no difference in the clinical performance of the two-crown types.

Therefore, this study will be conducted to compare and evaluate a clinical success of anterior aesthetic flexible crowns with anterior strip crowns in primary anterior teeth among children aged 3-6 years.