Among the 56 access holes, no filling was dislodged during 12 months, and no complaint was registered from the patients regarding functional and aesthetical aspects.

The results for surface areas changes of access-hole fillings at respective intervals were summarized in Table 3 and Fig. 6. The mean values of the change from T = 1 M to T = 12 M were 77.1 ± 13.1% for group M4M and 83.3 ± 11.5% for group CR, respectively. They were not statistically different (Mann-Whitney test p < 0.05, p = 0.046).

The contact distribution was as follows; A = 2, B = 14, and C = 40. The access-hole distributions were 24(CR) and 24(M4M) for the premolar/molar region, 4(CR) and 4(M4M) for the incisor/canine region, respectively. Among 16 access-holes, 11 of M4M and 5 of CR presented “B” (14) or “A” (2) occlusal contact mode. The average of the 11 (M4M) changes of the filling surface area at the time of T = 12 M was 77.1%. By pure coincidence, this mean value was identical to that of the 28 (M4M). For the 5 CR, the filling surface at T = 12 M was 85.3%. The average of the 28 CR was 83.3%.

The marginal depths of each access-hole (4 points) at T = 12 M were measured. The mean values for group CR were 141.2 ± 125.5 μm and 132.1 ± 107.8 μm for the group M4M, respectively. There was no significant difference between groups CR and M4M (Mann-Whitney test p > 0.05, p = 0.58).

The mean values of the angle at T = 12 M for group CR were 39.5 ± 19.4° and 28.2 ± 17.2° for group M4M, respectively. There was a significant difference (Mann-Whitney test p < 0.0001) between the groups CR and M4M. The marginal discrepancy patterns for both groups CR and M4M were different and shown in Fig. 7a, b.

Discoloration of the filling material as well as the marginal integrity was recorded at T = 0 and T = 12 M (Table 2). For the CR group, the mean VAS values were 8.64 at T = 0 and 7.43 at T = 12 M. The difference was 1.21 ± 1.37. For the M4M group, the mean VAS values were 8.71 at T = 0 and 7.50 at T = 12 M. The difference was 1.21 ± 1.52. No significant difference was found in CR and M4M groups (Mann-Whitney test p > 0.05, p = 0.848).