Discrepancy in alloy composition of imported and non-imported porcelain-fused-to-metal (PFM) crowns produced by Norwegian dental laboratories

Figures & data

Table 1. Elementary analysis in weight percentage (wt. %) for nonprecious alloys (CoCr), CopraBond K, Cara SLM, Kera-disc, Remanium 2001, Wirobond SG and Wirobond 280.

NON-PRECIOUS ALLOYS	Co	Cr	W	Mo	Mn	Fe	Si	Ga
CopraBond K	61.0	28.0	8.5		0.3	<0.5	1.7
Cara SLM	61.80–65.8	23.7–25.7	4.9–5.9	4.60–5.60	<0.1	<0.5	<1.2
Kera^®-disc	61.7	27.8	8.5		0.3	0.2	1.6
Remanium 2001	63.0	23.0	4.3	7.3	<1.0		1.6
Wirobond SG	63.8	24.8	5.3	5.1		✓	✓
Wirobond 280	60.2	25.00	6.2	4.8	✓		✓	2.9

Remanium 2001 also contains trace amounts of Nitrogen (N). Symbol (✓): Element stated to be present in unspecified trace amount according to manufacturer. Empty box: amount below detection limit.

Table 2. Precious alloys, d.SIGN 53, Argelite 61, Precious 1 and Precious 2.

PRECIOUS ALLOYS	Pd	Ag	Sn	In	Ru	Re	Li	Pt	Au	Ga
d.SIGN^®53	53.8	34.9	7.7	1.7	<1.0	<1.0	<1.0	<1.0
Argelite 61	60.6	28.1	2.5	6.6	<1.0	<1.0				2.1
Precious 1	61.4	26.0	6.0	4.0	0.1
Precious 2	53.7	35.7		1.0					1.0

Amounts stated in weight percentage (wt.%). Empty box: amount below detection limit.

Figure 1. Number of base-metal crowns sorted in categories according to degree of deviation (A: all base metals, B: Predominantly base metal base metal only C: noble metal base metal only.) No deviation: Minor deviations in major constituents (elements that comprises >20 wt. %) and slight deviations in additional elements that comprise <10 wt.%. Small deviation: <5 wt. % concerning major constituents and/or deviations >1 wt. % in additional elements that comprise <10 wt.%. Large deviation: >5wt. % concerning major constituents and missing and/or additional elements.

Figure 2. Whisker diagrams depicting distribution of data concerning alloy content deviation. Alloys ‘Noble’ (D) had large variations, hence the outliers in several of the constituents, whereas d.SIGN53 (B) showed little variation. *Noble metal diagram includes both Noble metal 1 and 2; these two alloys are both from Lab D and were termed Noble metal, however with slight differences in wt. % of each element. #statistically significant difference between the mean of the sampled population and the hypothesized population mean (p < .05).

Table 3. Distribution and number of base-metal crowns sorted in categories according to degree of deviation.

Alloy crown type	Distribution (%)
All crown alloys	Imported (n = 21)	Nonimported (n = 41)
No deviation	19 (n = 4)	15 (n = 6)
Small deviation	14 (n = 3)	32 (n = 13)
Large deviation	43 (n = 9)	20 (n = 8)
Incorrect alloy	N/A	2 (n = 1)
Unspecified alloy	24 (n = 5)	32 (n = 13)
Precious crown alloy	Imported (n = 12)	Nonimported (n = 20)
No deviation	25 (n = 3)	25 (n = 5)
Small deviation	N/A	30 (n = 6)
Large deviation	33 (n = 4)	25 (n = 5)
Incorrect alloy	N/A	N/A
Unspecified alloy	42 (n = 5)	20 (n = 4)
Non-precious crown alloy	Imported (n = 9)	Nonimported (n = 21)
No deviation	11 (n = 1)	5 (n = 1)
Small deviation	33 (n = 3)	33 (n = 7)
Large deviation	56 (n = 5)	14 (n = 3)
Incorrect alloy	N/A	5 (n = 1)
Unspecified alloy	N/A	43 (n = 9)
Category	Definition
No deviation	Minor deviations in major constituents (elements that comprises >20 wt.%) and slight deviations in additional elements that comprise <10 wt.%.
Small deviation	<5 wt.% in regard to major constituents and/or deviations >1 wt.% in additional elements that comprise <10 wt.%.
Large deviation	>5wt.% in regards to major constituents and missing and/or additional elements.
Incorrect alloy	Crowns that comprised of elements similar to a different type of alloy. For example a crown marked as CopraBond K with results showing elements such as silver (Ag) and palladium (Pd).
Unspecified alloy	Crowns delivered without or with lacking alloy information.

Figure 3. Information provided by the seven different dental laboratories showing level of ‘incorrect content’, ‘unspecified content’ and ‘specified content’.