Fracture resistance of extensive bulk-fill composite restorations after selective caries removal

Abstract

This study evaluated the effect of selective carious tissue removal on the fracture strength and failure mode of composite restorations in molars presenting only the buccal cusps. Deep cavities were prepared on the occlusal surface, and the lingual cusps were removed. Carious lesions in the middle of the pulpal wall were artificially induced with acetic acid (pH = 4.5) for 35 days. The demineralized dentin was left intact or was completely removed prior to restoration with a bulk-fill composite (n = 10). Images of the specimens were obtained by optical coherence tomography (OCT) before and after the caries induction/removal. The mechanical resistance to fracture by axial compressive loading and the failure type and extension were determined. The pulpal wall/composite interface of the fractured specimens was analyzed by OCT. The data were analyzed for significance with t-tests (α = 0.05). The deepest cavities and a more frequent occurrence of pulpal exposure were observed more often for non-selective carious tissue removal. The protocol of carious tissue removal did not affect the fracture strength (p = 0.554). An increased occurrence of catastrophic failures involving the roots was observed for non-selective carious tissue removal. Some occurrences of restoration displacement or cracks throughout the resin-dentin were observed only for the selective carious tissue approach. Selective carious tissue removal is a feasible approach to extensively damaged teeth since it reduced the occurrence of pulpal exposure and root fractures, without compromising the fracture strength.

Secondary Caries Adjacent to Bulk or Incrementally Filled Composites Placed after Selective Excavation In Vitro

“…The first studies, leaving caries lesions on the pulpal floor of occlusal cavities in molars, found a devastating impact of these lesions on restoration fracture resistance [ 2 ]. In a range of follow-up investigations, mainly on proximally located lesions in premolars, did not confirm this impact when assessing margin integrity, cuspal deflection, the formation of enamel cracks, and fracture strength [ 3 , 33 , 34 , 35 ]. Thus, it was argued that the location of the residual lesion is relevant.…”

Caries removal techniques: An update on relevant factors

“…Traditional caries removal involves the complete removal of carious tissue, with the aim of creating preventive margins to leave the boundaries of the restoration in healthy tissue [23] , mechanically preserving the restoration in the tooth, as well as ensuring the complete removal of bacteria [24] including color-changing dentin and preventing the development of the carious lesion process [15] . Drills and sharp hand instruments are used, which have the benefit of simplicity, speed and efficiency [4] , but also have major disadvantages, one of which is to establish the amount of dentin to be removed, since removing carious tissue also removes healthy tissue [25] . The removal of caries with rotary instruments showed a smooth surface with a typical dentin smear and occluded dentin tubules [26] .…”

“…Minimally invasive dentistry consists only of the removal of infected carious tissue and replacement with an adhesive restoration, so it is important to know the impact of the form of removal and the adhesives used to restore the tooth [2] . The conventional and traditional method of caries removal is the use of drills and burs [3] , which is effective and fast [4] . Some of the disadvantages of this technique are the risk of overextraction, vibration, noise, pain, discomfort and the need for local anesthesia [5] .…”

Atualidades Sobre a Remoção Seletiva De Cárie

“…Comparando os resultados entre as técnicas de remoção seletiva e remoção completa de cárie, os autores observaram que a técnica de remoção seletiva resultou em uma menor penetração marginal das restaurações de classe II, com uma diferença estatisticamente significativa. Santana et al (2020) compararam a resistência à fratura de restaurações de resina composta em dentes posteriores após a remoção seletiva e completa de cárie, e apontaram que a remoção seletiva de tecido cariado não afeta negativamente a resistência à fratura das restaurações de resina composta, uma vez que os resultados encontrados e a resistência à fratura foram semelhantes entre as duas técnicas de remoção.…”