Evaluation of the retention of prefabricated polyether ether ketone crowns compared to stainless steel crowns (an in vitro study)

Stainless steel crowns (SSCs) are widely recommended for primary molar restorations due to their long-term durability, low cost, and ease of preparation and application. While polyether ether ketone (PEEK) offers a potential aesthetic alternative, data on its performance in primary teeth is limited. This in vitro study aimed to evaluate several physical properties PEEK crowns in comparison to SSC on primary molars. This in vitro study evaluated 40 crowns divided equally into four groups: Prefabricated PEEK 0.2 mm (minimal prep), Prefabricated PEEK 0.4 mm (minimal prep), CAD/CAM PEEK (comprehensive prep), and SSCs (minimal prep). All crowns were cemented with glass ionomer cement. Retention strength, failure mode assessment, and surface roughness were tested. Data were analyzed using SPSS 21 with one-way ANOVA, Pearson’s chi-square, and independent samples t-tests at a significance level of p < 0.05. SSCs demonstrated significantly higher mean retention values than all PEEK groups (p < 0.05). Among the PEEK crowns, the prefabricated 0.2 mm variant showed the highest retention, followed by the prefabricated 0.4 mm and CAD/CAM designs. Failure mode distribution was significantly associated with crown material (p < 0.05). Furthermore, PEEK crowns exhibited a mean surface roughness approximately 3.7 times greater than that of SSCs (p < 0.05). While stainless steel crowns provided superior performance, prefabricated 0.2 mm PEEK crowns are a potential aesthetic alternative for low-stress situations, despite concerns regarding their higher surface roughness and plaque accumulation potential, necessitating further clinical study.