Page 167 - Clinical relevance of current materials for cranial implants

Liquid Chromatography/Mass Spectrometry (LC/MS)
Multiple peaks are visible in the HPLC spectrum of NextDent C&B MFH. LC/MS was performed to determine the substances present in these peaks and whether these are in fact related molecules with a common precursor. This leads to an increased concentration of released monomers (this was assumed in Table 2 & 3 and Figure 1). If this is not the case the concentration of released monomers is actually lower, but multiple different molecules are released. The MS spectra prove that these multiple peaks are indeed containing multiple related derivatives of the monomers in NextDent C&B MFH. No traces of other chemicals such as the initiator system, catalyst, or colorants were detected in the MS detector, indicating these substances were not present at concentrations above the detection limit.
Table 2: Cumulative residual monomer release in μg/g MMA per PMMA during 2 weeks incubation in water at 37 °C.
Time (hours) 1 2 4 8 12 24 48 72 168 336
Vertex Self- 18.02 Curing (1.85)
Leachables from materials used for cranioplasties
17.04 (1.66)
12.93 (1.37)
19.49 (5.63)†
25.63 (5.98)
Values given as mean and standard deviation (SD); n=3 8 †: n= 2
Palacos R+G
NextDent C&B MFH
DePuy CMW-3
8.31 (0.83)
21.94 (4.57)†
19.73 (4.10)
22.14 (0.98)
15.68 (1.74)
31.77 (0.23)†
35.67 (7.41)
27.51 (5.78)
17.07 (1.06)
32.68 (0.47)
47.74 (8.58)
29.62 (5.20)
19.07 (3.31)
30.68 (0.20)†
54.76 (12.12)
41.04 (7.53)
24.87 (0.30)
30.23 (7.02)
61.81 (13.49)
46.47 (6.22)
31.61 (0.79)†
28.40 (5.90)
74.05 (13.67)
49.05 (4.49)
33.41 (0.95)†
24.89 (4.26)
97.81 (7.14)
50.59 (1.96)
38.33 (2.26)
22.47 (1.32)†
84.70 (14.63)
46.26 (2.23)
42.54 (3.49)
22.75 (4.05)
78.83 (7.67)
Table 3: Pseudo first order (Y = Y0 * (1 – exp(-k*X))) release
C&B MFH. X = time in hours; Y = quantity MMA per PMMA in μg/g; k = constant; τ = half-life in hours; Td = doubling time in hours
Material
Vertex Self-Curing Palacos R+G NextDent C&B MFH DePuy CMW-3
Y0
46.6 (42.8-50.3) 36.7 (33.0-40.2) 27.7 (25.2-30.1) 81.0 (73.8-88.2)
kτ
Td R2
5.37 (4.09-7.81) 0.75 9.28 (6.98-13.84) 0.79 0.59 (0.50-2.91) 0.13 6.16 (4.61-9.29) 0.78
profiles of Vertex Self-Curing, Palacos
R+G, and
NextDent
0.13 (0.09-0.17) 0.07 (0.05-0.10) 1.17 (0.34-1.99) 0.11 (0.07-0.15)
7.75 (5.90-11.3) 13.4 (10.0-20.0) 0.86 (0.50-2.91) 8.89 (6.65-13.4)
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