Fracture resistance of prefabricated versus custom-made zirconia crowns after thermo-mechanical aging: an in-vitro study.

BACKGROUND: Prefabricated zirconia crowns for a young permanent molar is a child-friendly solution for restoring a permanent molar at a young age. This in-vitro study aimed to compare the fracture resistance of prefabricated versus custom-made permanent molar crowns. METHODS: 16 identical resin dies were fabricated to receive permanent molar zirconia crowns, dies were divided into 2 groups, 1) received perfricated crowns, 2) custom-made crowns. Thermo-dynamic cycling was performed to simulate 6 months in the oral cavity, Fracture resistance of each group was assessed by applying increasing load till fracture. Data were tested for normality using Shapiro-Wilk and Levene's tests. Data were analyzed using independent t test. RESULTS: No statistically significant difference was found between fracture resistance of prefabricated and custom-made crowns (1793.54 ± 423.82) and (1987.38 ± 414.88) respectively. 3 crowns of the custom-made group fractured with the underlying die, versus zero dies fractured in the prefabricated group. CONCLUSIONS: Prefabricated permanent molars zirconia crowns can perform as well as custom-made crowns for an adult in terms of fracture resistance, it is suitable for children and can withstand the occlusal forces of an adult.

Clinical and radiographic evaluation of indirect pulp treatment of young permanent molars using photo-activated oral disinfection versus calcium hydroxide: a randomized controlled pilot trial.

BACKGROUND: Calcium hydroxide is the most commonly used material in indirect pulp treatment (IPT). However, its drawbacks required its replacement by other materials. AIM: This study aims to estimate clinically and radiographically the success of indirect pulp treatment of young permanent molars with either photo-activated oral disinfection (PAD) or calcium hydroxide. DESIGN: This Randomized Controlled Pilot Trial included 32 vital first permanent molars with deep caries that were treated by indirect pulp treatment with either PAD (group 1) or calcium hydroxide (group 2). Clinical and radiographic success in addition to newly-formed dentin thickness were evaluated regularly at 2, 6, 9, and 12 months. RESULTS: The success for both groups was 100% clinically and radiographically at all follow-up periods. Regarding the mean thickness of newly-formed dentin for both groups at different follow-up periods, there was no statistically significant difference between both groups at 2, 6, 9, and 12 months, with P values = 0.825, 0.146, 0.280, and 0.400, respectively. CONCLUSIONS: The clinical and radiographic success for indirect pulp treatment of young permanent molars with both PAD and calcium hydroxide were comparable.

Influence of luting cement on the clinical outcomes of Zirconia pediatric crowns: A 3-year split-mouth randomized controlled trial.

BACKGROUND: There is no scientific evidence supporting the choice of luting cement for cementation of zirconia crowns. AIM: The purpose of this split-mouth study was to compare the efficacy of using bioactive cement versus packable glass ionomer for cementation of posterior pediatric zirconia crowns. DESIGN: Fifty first mandibular primary molars were restored by zirconia crowns and were randomly divided to be luted with either (a) bioactive cement or (b) packable glass ionomer. Crowns' retention, fracture, and gingival condition were evaluated at 1 week, and 1-, 3-, 6-, 9-, 12-, 18-, 24-, and 36-month intervals. Statistical analysis was carried out using Fisher's exact test, Kaplan-Meier survival analysis, and Wilcoxon signed rank test. RESULTS: At 3- to 36-month follow-ups, there were statistically significant (P = .009-≤.001) less debonded crowns in packable glass ionomer group. There were no fractured crowns for either cements. There was no statistically significant difference between gingival index scores. CONCLUSIONS: Packable glass ionomer is more retentive than bioactive cement when used for cementing zirconia pediatric crowns. Posterior zirconia pediatric crowns have high fracture resistance after 36 months of clinical performance, irrespective of luting cement. Luting cement for zirconia pediatric crowns has no apparent effect on gingival condition around crowns.

Successful Restoration of Severely Mutilated Primary Incisors Using a Novel Method to Retain Zirconia Crowns - Two Year Results.

AIM: This manuscript describes a simple reliable technique for restoring severely mutilated primary anterior teeth. A rigid glass ionomer post is created over which zirconia crowns can be fitted to achieve a long-term stable esthetic restoration for primary anterior teeth. STUDY DESIGN: Children aged 2-5 years with two up to six extensively decayed upper primary incisors were included. Fuji IX was condensed into an intracanal space created to a depth of 3mm, to provide a core which also extended 3mm supragingivally. Crown preparations were completed upon these cores. Zirconia crowns (Nusmile, Houston Texas USA) were fitted and cemented over the prepared cores. All patients were recalled at regular intervals. RESULTS: Twenty-three healthy children with 86 restorations participated in the study. The overall survival of the restorations was 95.3% after 12 months and 80.2% after 24 months. According to Kaplan-Meier survival analysis, the median survival time was not reached while the estimated mean survival time was 22.9 months. CONCLUSIONS: This newly described clinical technique is simple and reliable to use for restoration of extensively decayed primary incisors. Use of zirconia crowns retained using this technique offers superior esthetic, durable restorations with remarkable gingival response up to 24 months.