Influence of gaps in adhesive restorations in the development of secondary caries lesions: an in situ evaluation.
OBJECTIVE
To investigate in situ the influence of gaps in the development of secondary caries lesion in adhesive restorations.


METHODS
10 volunteers utilized intra-oral appliances, containing three human dental blocks (enamel and dentin), representing the three different groups (two restored, one sound): (1) restored with resin composite using the total acid etch adhesive technique (37% H3PO4 + Single Bond + Z250); (2) restored with resin composite but without acid etching (Single Bond + Z250); (3) and sound blocks (control group). The dental blocks (n=30) were randomly positioned inside the intra-oral appliances, and covered by a porous tissue (gabardine base) to induce a cariogenic biofilm. The volunteers used the appliances 24 hours daily for a 28-day period, removing just during meals and oral hygiene. Eight times a day, a 20% sucrose solution was dripped onto the blocks. Five minutes later, the appliance was washed with distilled water and replaced in the oral environment. After the experimental period, the dental blocks were removed from the appliance and examined by visual examination to detect the presence or the absence of an active carious lesion (kappa= 0.89). Posteriorly, they were prepared for the polarized light microscopy examination, which was performed to describe enamel surface characteristics on the restored and unrestored blocks with active caries lesion (kappa= 1).


RESULTS
The visual examination demonstrated that almost all (29/30) of the blocks showed non-cavitated active caries lesion on the enamel surface. The microscopic evaluation showed non-cavitated caries lesions on enamel surfaces for all groups. In the restored blocks (with and without the total etch technique), the demineralization was first identified as an outer lesion that follows the enamel prism directions, and in some cases, reached the cavity walls. The results showed that caries lesion development adjacent to the restoration was determined by the cariogenic challenge of the oral environment, instead of the restoration adhesive quality, and the wall lesion was determined by the prism orientation, regardless of the presence of gaps.
School of Dentistry, Department of Pediatric Dentistry, Federal University of Rio Grande do Sul, Ramiro Barcelos 2492, Bom Fim, Porto Alegre-RS, 90.035-003, Brazil.
Juliana Sarmento
JS
Barata
Luciano
L
Casagrande
Carla Moreira
CM
Pitoni
Fernando Borba
FB
De Araujo
Franklin
F
Garcia-Godoy
Sonia
S
Groismann
D000134:Acid Etching, Dental; D017438:Bisphenol A-Glycidyl Methacrylate; D003188:Composite Resins; D001840:Dental Bonding; D003731:Dental Caries / Q000209:etiology*; D003733:Dental Caries Susceptibility; D003743:Dental Enamel / Q000033:anatomy & histology*; D018772:Dental Marginal Adaptation; D003793:Dental Restoration, Permanent; D006801:Humans; D019279:Resin Cements
D003188:Composite Resins; C444701:Filtek Z250; D019279:Resin Cements; C115612:single bond; D017438:Bisphenol A-Glycidyl Methacrylate