Influence of the Number of Layers of a One Bottle Adhesive on the Longevity of Composite Restorations in Primary Molars

Influence of the Number of Layers of a One Bottle Adhesive on the Longevity of Composite Restorations in Primary Molars

Influence of the Number of Layers of a One Bottle Adhesive on the Longevity of Composite Resin Restorations in Primary Molars - Randomized Controlled Clinical Study.

The aim of this study is to determinate the influence of an alternative adhesive application protocol (i.e. consecutive application of an extra adhesive layer)on restoration longevity in primary molars.

Adhesive systems based on total etch technique remains the most popular products among dental practitioners. These systems are based on the use of an acid conditioner to remove the smear layer and demineralize the enamel and dentin. After the removal of the conditioner by rinsing, a mixture containing the primer and adhesive - i.e. one bottle adhesives - is applicated over the demineralized tissues. The polymerization of the adhesive monomers into microporosities created by acid conditioning forms the structure knowing as hybrid layer or resin-dentin interdifusion zone. A common problem related to total etch technique is the incomplete infiltration of adhesive monomers through demineralized dentin, resulting in the presence of a zone of unprotected collagen fibrils beneath the hybrid layer that is prone to enzymatic degradation. According to some laboratory studies, consecutive application of multiple adhesive coats results in quantitative and qualitative improvements in dental adhesion. In addition to increasing the values of bond strength to dentin, consecutive application of multiple adhesive layers enhances the infiltration of adehesive monomers through demineralized dentin, resulting in a more homogenous hybrid layer.

After caries removal, enamel margins will be conditioned with phosphoric acid gel 37% by 15 seconds and dentin walls by 8 seconds. The etchant will be removed with use of water spray by 30 seconds. The water excess will be removed with a cotton pellet. The first layer of Prime & Bond 2.1 adhesive will be applied with a microbrush. After 20 seconds a second layer will be applied and after a similar period a third layer will be applied over cavity walls. Again, after 20 seconds, the layers will be gently air-dried and photopolymerized by 10 seconds with a LED photoactivation unit.

After caries removal, enamel margins will be conditioned with phosphoric acid gel 37% by 15 seconds and dentin walls by 8 seconds. The etchant will be removed with use of water spray by 30 seconds. The water excess will be removed with a cotton pellet. The first layer of Prime & Bond 2.1 adhesive will be applied with a microbrush. After 20 seconds a second layer will be applied and after 20 seconds, the layers will be gently air-dried by 5 seconds. The two layers will be photopolymerized by 10 seconds with a LED photoactivation unit.

Survival rate considering failure of restorations due: partial or complete loss of restorative material; marginal ditching; superficial or marginal discoloration; secondary caries; pulpal complications; wear of restorative material; tooth fracture.

Inclusion Criteria: Presence of two or more pairs of caries lesions in occlusal or occluso-approximal surfaces of primary molars Exclusion Criteria: Systemic diseases in which dental treatment is a risk to patient's life Bruxism Orthodontic appliance Absence of occlusal contact in eligible teeth Signs and symptoms of pulp infflamation or necrosis

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