In Vitro Comparison of Fracture Resistance of Severely Damaged Primary Anterior Teeth Restored with Different Post and Core Systems.

Objectives: This study aimed to compare the fracture resistance (FR) of severely damaged primary anterior teeth restored with five different post and core systems. Materials and Methods: This in vitro, experimental study evaluated 60 extracted primary maxillary central incisors. The teeth were horizontally sectioned at 1 mm above their cementoenamel junction (CEJ), underwent pulpectomy, and their root canals were filled with Metapex paste. After post space preparation and sealing of root fillings with light-cure glass ionomer (1 mm thickness), the teeth were randomly assigned to five groups (n = 12) of (1) glass fiber post and everX composite (reinforced with short fibers), (2) glass fiber post and bulk-fill composite, (3) everX composite post and core, (4) bulk-fill composite post and core, and (5) Filtek conventional composite post and core. The teeth underwent 5,000 thermal cycles between 5°C and 55°C, and their FR was measured in a universal testing machine (0.5 mm/min, 148°). The mode of failure was also determined. Data were analyzed by ANOVA and Tukey's test at 0.05 level of significance. Results: The FR was the highest in fiber post and everX composite, and the lowest in Z250 conventional composite post and core group (P < 0.001). The FR of fiber post and everX composite group was significantly higher than that of everX composite post and core (P = 0.04), bulk-fill composite post and core (P = 0.001), and Z250 composite post and core (P < 0.001) groups. The frequency of repairable fractures was the highest in glass fiber post plus everX composite (91.66%) and the lowest in Filtek conventional post and core group (66.66%) (P > 0.05). Conclusion: Within the limitations of this in vitro study, the results showed that restoration of severely damaged primary maxillary central incisors with glass fiber post and everX composite reinforced with short fibers enhanced their FR, and increased the chance of reparability in case of restoration fracture. This technique may be recommended for the restoration of primary anterior teeth since it is simple and saves time.

Effect of two different concentrations of 1α,25-dihydroxyvitamin D3 on odontogenic differentiation of stem cells from human exfoliated deciduous teeth.

Background: Stem cells from human exfoliated deciduous teeth (SHEDs) can transform into odontoblasts in vitro and in vivo. The role of 1α, 25-dihydroxyvitamin D3 (1α,25 vitD3) has been reported in the mineralization of hard tissues and teeth, as well as osteoblastic differentiation. This study aimed to assess the effect of different concentrations of 1α,25 vitD3 on odontogenic differentiation of SHEDs. Materials and Methods: In this experimental study, second-passage SHEDs were exposed to odontogenic medium along with 0, 10, 50, 100, and 150 nmol concentrations of in 1α, 25 vitD3 to determine its optimal concentration for odontogenic differentiation. The methyl thiazolyl tetrazolium (MTT) assay was performed. Odontogenic differentiation was evaluated by QRT- polymerase chain reaction for dentin matrix protein (DMP1) and dentin sialophosphoprotein (DSPP) genes. Morphology of differentiated cells was studied by Scanning Electron Microscopy. Data were analyzed using the Kruskal-Wallis, Mann-Whitney, Friedman, and Chi-square test. P < 0.05 is considered statistically significant. Results: MTT test result showed the two groups of odontogenic medium + 10 nm 1α,25 vitD3 and odontogenic medium + 150 nm 1α,25 vitD3 provided the most suitable conditions for cell viability at 72 h. Expression of both genes significantly increased in the presence of 1α,25 vitD3 (P < 0.001). Expression of both genes was significantly higher at 14 days compared with 7 days (P < 0.01). At both time points, expression of both genes was significantly higher in the presence of 150 nm 1α,25 vitD3 compared with 10 nm (P < 0.01). The accumulation of cells with odontoblastic morphology, cell interactions, and calcifications were evident. Conclusion: 1α,25 vitD3 upregulates DMP1 and DSPP and results in odontogenic differentiation of SHEDs in odontogenic medium. This upregulation increases with time and by an increase in concentration of 1α,25 vitD3.

Endodontic Treatment of a Tooth with Traumatic Fracture of Root Middle Third.

Root fracture occurs in 0.5 to 7% of all dental injuries. Subsequent to this injury, the coronal segment is displaced, while the apical segment is rarely displaced. Emergency treatment involves repositioning of the coronal segment close to the radicular segment as much as possible to enhance the chance of pulp revascularization. If pulp necrosis occurs, the infective products cause an inflammatory response and radiolucency is seen at the fracture line. In the present case, the patient had two maxillary central incisors with horizontal middle third root fractures due to a traumatic accident four years earlier. The right central incisor showed an endodontic abscess due to pulp infection in the coronal segment. The coronal fragment was treated. In this case study all signs and symptoms resolved after treatment and three year follow-up showed a successful treatment outcome. The left central incisor had a vital pulp according to vitality tests, so "observation only" strategy was considered for this tooth.

One-Year Clinical Success of Embrace Hydrophilic and Helioseal-F Hydrophobic Sealants in Permanent First Molars: A Clinical Trial.

OBJECTIVES: This study sought to compare the one-year clinical success of a hydrophilic and a hydrophobic fissure sealant in permanent first molars. MATERIALS AND METHODS: This split-mouth clinical trial was conducted on 23 six to nine year olds who had four fully erupted sound first molars. Helioseal-F and Embrace sealants were randomly applied on the first molars, and follow-ups were scheduled at three, six and 12 months to examine the teeth according to USPHS criteria (retention, marginal adaptation, color match, surface smoothness and caries recurrence). The Wilcoxon signed rank test, the Friedman test and the Mann Whitney test were applied for statistical analyses (P<0.05). RESULTS: No significant differences were noted between Embrace and Helioseal-F in retention, smoothness of surface, marginal adaptation, color match or caries at three, six or 12 months (all P>0.05). In addition, the retention of sealants between the maxilla and mandible was not significantly different (P>0.05). Friedman test revealed no significant difference in any of the five parameters at different time points in any sealant group (P>0.05). CONCLUSIONS: Embrace hydrophilic and Helioseal-F hydrophobic sealants have the same one-year clinical success rate.

The Callender modification of the Macintosh laryngoscope blade reduces the risk of tooth-blade contact in children.

BACKGROUND: Dental injury is well recognized as a potential complication of laryngoscopy and tracheal intubation. The flange of the Macintosh blade may contact teeth during laryngoscopy causing damage. The Callander modification of the Macintosh blade (Callander blade) with a shortened heel at the proximal end has been shown to increase the blade-tooth distance and reduce contact rates in adults. AIM: This study was designed to evaluate the effectiveness of the Callander blade on reducing dental contact in children. METHODS: One hundred children, aged 4-14 years, scheduled for general anesthesia requiring endotracheal intubation were studied prospectively. The children were preoperatively evaluated for Mallampati score and dental defects, looseness, and avulsions. Following induction of anesthesia, laryngoscopy was performed twice on each child in succession, once with a standard Macintosh blade and once with a Callander blade of the same size in a random order. The blade-tooth distance and contact rate were compared between the two blades. RESULTS: With the Callander blade, the blade-tooth distance was greater than with the Macintosh (1.78 +/- 1.77 vs 0.28 +/- 0.76 mm, P = 0.001). The frequency of direct contact was less with the Callander blade than it was with the Macintosh blade (33% vs 86%, respectively, P = 0.008). However, difficult laryngoscopy rate did not differ between the blades. Tracheal intubation was successful in all children and there was no dental injury. CONCLUSION: Our findings suggest that the Callander blade decreases the risk for dental injury and provides tracheal intubating conditions in children with normal airways similar to those obtained with a traditional Macintosh blade.

The effect of bonding agents on the microleakage of sealant following contamination with saliva.

AIMS: An issue of concern in dentistry is the inadequacy of adhesion and proper sealing following restoration of a tooth, which can lead to marginal leakage. The aim of this study was to evaluate the effect of a bonding agent on the microleakage of a sealant material following contamination with saliva. MATERIALS AND METHODS: In this experimental research, 48 sound premolars were divided into two groups. The first group received sealant without bonding and the other group was given sealant with bonding. After prophylaxis, the occlusal surfaces were etched with 37% phosphoric acid gel and the teeth were then placed in fresh human saliva for l0 s. Following this, in the first group fissure sealant (Kerr) was applied directly and cured; for the second group sealant was placed and cured after bonding (Single Bond; 3M). All samples were thermocycled (500 cycles; between 5 degrees C and 55 degrees C; dwell time of 30 s). Silver nitrate was used as the leakage tracer. The teeth were sectioned. Microleakage evaluation was made by stereomicroscope at 40x magnification and the results were evaluated with the Mann-Whitney U test. RESULTS: In the group that received sealant without bonding extensive microleakage was seen; placement of sealant with bonding significantly reduced microleakage. CONCLUSION: In the presence of contamination with saliva, use of bonding under the fissure sealant can reduce microleakage.