Resin fissure sealants were introduced in child and adolescents dental health care in the late 1960s and early 1970s in Denmark. Since the initial experience was good, sealing of first molars’ occlusal surfaces shortly after tooth eruption was a regular caries preventive treatment in the 1980s. Today, due to the improved dental health, resin sealants on occlusal surfaces are mainly used based on indication, i.e. surfaces with progressive enamel lesions.
Previous studies indicate that progression of the occlusal caries lesion may be arrested with resin sealants provided that the sealant is tight. Demineralization will stop and the sealed dentinal lesions become bacteriologically inactive over time. At the same time the consistency of the dentin lesion will change; thus, the lesions become dry and leathery as a sign of inactivity if the lesion is opened. However, it is not common to use resin sealants on medium deep or deep dentinal lesions; and only few studies examine the effect of resin sealants of lesions in adult patients.
The progression of dentinal caries lesions are evaluated radiographically based on scores of lesion depth by paired comparison of X-rays, or by subtractions radiography. All three methods have their limitations, and it is difficult to assess whether a lesion has progression, unchanged or even regression during a follow-up period. A precise and reproducible method for measuring the lesion extension has been desirable.
The purpose of this thesis was to investigate the effect of resin sealing of occlusal lesions in adult patients which were assessed to be in need of restorations according to the current treatment strategies. At the same time the purpose was to develop a method to measure radiological lesion extension.
The clinical study included 52 patients with 72 teeth with primary occlusal lesions. Randomization was performed in cases of more than one lesion in the same patient, so that the final material consisted of 60 resin sealed and 12 restored lesions. After 2-3 years, there was a drop-out of 15%; 2 patients did not show up for the control and 9 previously sealed lesions were restored by patients' GP. All 12 restorations and 39 of the remaining 49 sealants were well-functioning (p = 0.18). Additional 7 sealants (14%) were repaired or replaced and 3 sealants (6%) were restored during the follow-up period. By paired comparison of the radiological extension of the lesions from baseline and the last control radiograph, there was scored caries progression beneath 5 (10%) of 49 sealants, caries regression beneath 1 (2%) sealant and unchanged lesion depth beneath 43 (88%) sealants and all restorations (p = 0.64).
The methodological study included 110 permanent molars with occlusal lesions in different stages. The lesions were visually scored with ICDAS scoring system then sectioned into a facial and a lingual fraction. Digital radiographs and macroscopic photos of each fraction were taken. After randomization, the facial or the lingual fraction of each tooth was color-dyed with Caries Detector®, and digitally photographed.
The maximum width and the deepest extent of the lesions, enamel-dentin-junction and enamel-cement-junction were marked, and their relative dentinal depth and width were measured in the 2 histological images before and after dying, as well as on the radiographical images. Significant correlation was found between ICDAS scorings and the measured depth and width of the lesions on the histological images before and after color-dying and radiographically. However, there was a tendency to underestimate the histological depth of the lesions with ICDAS. Furthermore, the results showed that there was only a slight difference in the relative depth and width of the lesions measured histologically before and after color-dying, but that the histological extension of the lesions were generally greater than the radiographical.
The measurement method was subsequently used to assess the radiological extension of the lesions in the clinical trial. The relative depth was measured on the digitized radiographs from baseline and the last control of the 49 sealed lesions which could be followed in 2-3 years. Measurements showed unchanged depth in 40 (82%) lesions, progression in 2 (4%) and regression in 7 (14%) lesions. Caries lesions with no clinical cavity formation showed full retetntion of sealant and no progression, while lesions with enamel or dentin cavities showed cases with deficient retetntion as well as caries progression. Significant correlation was found between the retention of the sealants and the need for re-treatment of the lesion.
Based on the obtained results it can be concluded that the resin sealing is an effective treatment in arresting caries progression of medium deep and deep occlusal caries lesions which were in need of restoration in adult patients. Frequent control intervals are necessary to follow the clinical and radiographical changes of the sealed lesions. With the developed measurement method, it is possible to measure the relative depth and width of occlusal caries lesions histological and radiographical with high accuracy and reproducibility. This method can now be used in monitoring occlusal lesions progression as well as regression in clinical investigation.