Is zirconium or stainless steel the most suitable crown material for less dentin stress in endodontically treated teeth?

BACKGROUND: Stainless steel crowns (SSCs), which have been used frequently in the treatment of first permanent molars in children until now, has become less applicable due to its poor aesthetic appearance. Zirconia crowns (ZCs) have become more popular due to their aesthetic advantage. However, stress transmission of ZCs to dental tissues under occlusal forces in endodontically treated teeth has not been described. OBJECTIVE: The aim of this study was to compare the stress distribution of different crown materials (ZCS, SSCs) and adhesive materials on dentin in endodontically treated permanent teeth and to specify the crown-adhesive model with lower stress. METHODS: Finite element analysis (FEA) was used to apply a force of 300 N from the inner part of the buccal tubercles (vertical loading) and a lingo-buccal at an angle of 30 degrees (oblique loading) of the first permanent molars (FPM) with different crown (ZCS, SSCs) and adhesive (Glass ionomer cement, Resin modified glass ionomer cement, Resin cement) materials in twelve separate models. The von Mises values obtained from the models were compared and the optimal stress values were determined by FEA. RESULTS: The lowest stress values of dentin were found in zirconia crown model with glass ionomer cement (GIC) adhesive under vertical loading (26,793 Mpa). In the zircon crown and GIC adhesive model, less von Mises stress occurred on the dentin under all conditions. CONCLUSIONS: ZCs and GIC adhesive may be recommended for teeth with a high probability of dentin fracture.

Traumatic Dental Injuries Occurred in Primary Teeth and their Sequel Effects on the Developmental Permanent Successors: A Controlled Study

ABSTRACT Objective: To examine the types of traumatic dental injuries of the primary teeth (TDI-p) and the long-term sequelae on permanent dentition (LSP) comparing with a control group (CG). In addition, a questionnaire that measures parents' knowledge and awareness was used. Material and Methods: The trauma group (TG) consisted of permanent teeth following TDI-p exposed teeth, while the CG consisted of permanent teeth following unexposed teeth with TDI-p of the same patients. In total, 141 teeth were evaluated in 27 patients. Data concerning such as teeth, when TDI-p occurred, types of treatments and types of LSP were collected. Chi-square test was used for intergroup comparison for gender, type of trauma, LSP, age of trauma and parameters in the parental information questionnaire. Significance level was p<0.05. Results: A statistically significant difference was found in the analysis between TG and CG (p<0.001). The prevalence of LSP due to TDI-p was 29.6% and the prevalence of sequelae in CG was 7.4%. The most common LSP was enamel hypoplasia (14.8%). Parents were aware of the importance of TDI-p, and they had insufficient knowledge about its management. Conclusion: TDI-p can be considered a high-risk factor in the development of LSP. Also, the lack of knowledge in parents should be supported by software-based application systems to be developed.

Comparison of the effects of new folkloric hemostatic agent on peripheral nerve function: an electrophysiologic study in rats.

OBJECTIVE: The aim was to evaluate the effects of a new folkloric medicinal plant extract on peripheral nerve function compared with oxidized regenerated cellulose (OC) and bovine collagen (BC). STUDY DESIGN: Under ketamine anesthesia a total of 40 male Sprague-Dawley rat right sciatic nerves were identified. Animals were randomly divided into 5 groups: OC, BC, ankaferd blood stopper (ABS), and negative and positive control groups. The recordings of nerve potentials were carried out using an electrophysiologic data acquisition system. After the application of substances, the nerve conduction velocity (NCV) was recorded for immediate (30 min), early (120 min), and delayed (3 wk) effects on nerve function. RESULTS: Statistically, differences were not found among the hemostatic agents (OC, BC, and ABS) at baseline and all tested periods (early, immediate, and delayed; P > .05). The positive control group exhibited lower NCV values compared with the other solutions at the 30-minute period (P < .05) as well as the other tested time periods (P > .05). OC exhibited NCV values closer to the positive control group at 120 minutes (P > .05). CONCLUSIONS: Folkloric medicinal hemostatic agent could be considered as an acceptable hemostatic material without resulting in any serious peripheral nerve function alterations. The possible desirable effects of bovine collagen and undesirable effects of oxidized cellulose on peripheral nerve function should not be overlooked.

Clinical and radiographic outcomes of calcium hydroxide and formocresol pulpotomies performed by dental students.

OBJECTIVE: The aim of this study was to compare the clinical and radiographic success rates of 3 pulpotomy techniques: formocresol, calcium hydroxide, and calcium hydroxide/iodoform. STUDY DESIGN: The pulpotomies were performed by fifth-year undergraduate dental students. Members of senior staff at the clinics supervised all of the procedures. Informed consent was obtained from each child's parents. The teeth were randomly assigned to the experimental (calcium hydroxide and calcium hydroxide/iodoform) or control (formocresol) groups. After coronal pulp removal and hemostasis, remaining pulp tissue was covered with calcium hydroxide or calcium hydroxide/iodoform paste in the experimental groups. In the control group, formocresol was placed with a cotton pellet over the pulp tissue for 5 minutes and removed; the pulp tissue was then covered with zinc oxide-eugenol. All teeth were restored with stainless-steel crowns. Clinical and radiographic successes and failures were recorded at 1-, 3-, 6-, and 12-month follow-ups by the authors. Data were statistically analyzed using chi-squared tests. RESULTS: The follow-up evaluations revealed that the clinical success rates were 89.7% for formocresol, 33.3% for calcium hydroxide, and 17.2% for calcium hydroxide/iodoform. The radiographic success rates were 89.7% for formocresol, 33.3% for calcium hydroxide, and 13.8% for calcium hydroxide/iodoform. CONCLUSIONS: Formocresol was superior to calcium hydroxide and calcium hydroxide/iodoform pastes for primary molar pulpotomies. Internal resorption was the most common radiographic failure in all 3 pulpotomy techniques.