Analysis of radiologic factors in determining premolar root canal systems

OBJECTIVES: Certain tooth groups pose problems as to radiologic determination of root canal morphology. For example, the premolars may have superimposed roots that give the appearance of a single canal when 2 are actually present. This study examined the effect of X-ray tube inclination so as to visualize the complete root canal system in premolars. STUDY DESIGN: One hundred extracted premolars were divided into 4 groups of 25 teeth each: 1MxP (first maxillary premolar), 2MxP (second maxillary premolar), 1MdP (first mandibular premolar), and 2MdP (second mandibular premolar). A total of 10 radiographs were made of each tooth in the horizontal and vertical planes (horizontal angles of 0, 20, and 40 degrees, then vertical angles of 0, 15, and 30 degrees). Logistic regression analysis was used for the statistical analysis of the results--the dependent variable being the number of canals visualized. RESULTS: On varying the horizontal angle (20 and 40 degrees), the number of root canals observed in the case of 1MxP, 2MxP, and 1MdP coincided with the actual number of canals present. In the case of 2MdP, only the 40 degree horizontal angle correctly identified the number of canals regardless of the vertical angle (although only 4% had more than 1 canal). CONCLUSIONS: Varying the horizontal angle improved the visualization of additional (superimposed) canals in premolars. Changing of the vertical angle had no statistically significant influence except for the first mandibular premolars.     

Intracanal reinforcement fiber in pediatric dentistry: a case report.

A technique for the restoration of carious primary maxillary incisors using indirect resin composite crowns and intracanal reinforcement fiber is described. Endodontic treatment was previously performed on each tooth. The advantages of using an intracanal reinforcement fiber include resin composite crown reinforcement, translucency, and relative manipulation facility. In addition, the use of indirect resin composite crowns provides good shape and esthetics, as well as reduced chair time for the child. The technique is illustrated in a case report in which indirect resin composite crowns and an intracanal reinforcement fiber are placed in a 3-year-old girl.     

Immediate Loading of Palatal Implants in Stillgrowing Patients: a Prospective, Comparative, Clinical Pilot Study

OBJECTIVE: The objective of this prospective, comparative study was to evaluate the potential of allowing immediate (within 72 hours) loading of palatal implants used for maximum orthodontic anchorage. This is in contrast to the standard protocol calling for a healing period of 12 weeks. MATERIALS AND METHODS: Sixteen patients with a mean age of 14.22+/-1.37 years for whom orthodontic treatment with maximum anchorage was indicated were randomized into two groups. In the SB (immediate loading) group (n=8, mean age 14.15+/-1.2 years), the implants were employed to provide maximum anchorage for a 1.2 x 1.2 mm TPA wire in combination with a molar band within 72 hours of insertion. In the KB (conventional loading) group (n=8, mean age 14.30+/-1.57 years), the implants were not used for maximum anchorage until a 12-week healing period had elapsed. Patients in both groups with implants that were clinically unstable after insertion were excluded from the study. After conclusion of the treatment, the implants were explanted and embedded using the sawing-grinding technique after Donath. Bone-implant contact (KIK) was analyzed using Bioquant Osteo software version 7.10.10. RESULTS: The objective of the orthodontic treatment, to achieve maximum anchorage of the first molars, was achieved in both groups. In the SB group, the mean bone-implant contact was 55.0%+/-21.6. In the KB group, the mean bone-implant contact was 73.1%+/-19.8. With a p-value of 0.1661, the difference between the bone-implant contact values was not statistically significant. CONCLUSION: The results of our clinical study demonstrate that when implants are clinically stable following insertion, it seems that a 12-week healing phase during which the implants are not loaded leads to a non-statistically significant improvement in osseointegration.     

Bilateral bifid mandibular condyle: case report and literature review

Bifid mandibular condyle is an infrequent and normally asymptomatic morphological alteration of the mandibular condyle. Although the underlying cause is not clear, a number of theories have been proposed, including teratogenic effects in the embryo, vascular alterations during condyle development, and condylar remodeling following fracture. Since Schier first described this anomaly in 1948 in live individuals, further cases have been documented in the literature. We present a new case of bilateral bifid condyle. The disorder was asymptomatic and constituted a casual finding in a young male presenting for the surgical extraction of two impacted molars.     

Resistance to maxillary premolar fractures after restoration of class II preparations with resin composite or ceromer.

OBJECTIVE: The aim of this study was to evaluate the resistance to fracture of intact and restored human maxillary premolars. METHOD AND MATERIALS: Thirty noncarious human maxillary premolars, divided into three groups of 10, were submitted to mechanical tests to evaluate their resistance to fracture. Group 1 consisted of intact teeth. Teeth in group 2 received mesio-occlusodistal cavity preparations and were restored with direct resin composite restorations. Teeth in group 3 received mesio-occlusodistal cavity preparations and were restored with ceromer inlays placed with the indirect technique. After restoration, teeth were stored at 37 degrees C for 24 hours and then thermocycled for 500 cycles at temperatures of 5 degrees C and 55 degrees C. RESULTS: Statistical analysis revealed that group 3 (178.765 kgf) had a significantly greater maximum rupture load than did group 1 (120.040 kgf). There was no statistically significant difference between groups 1 and 2 or between groups 2 and 3. CONCLUSION: Class II cavity preparations restored with indirect ceromer inlays offered greater resistance to fracture than did intact teeth. The fracture resistance of teeth restored with resin composite was not significantly different from that of either the ceromer or intact teeth.     

Hydrolytic stability of experimental hydroxyapatite-filled dental composite materials.

OBJECTIVES: The purpose of this study was to analyze the behavior in water, related to mechanical properties, of experimental composites for dental restoration. METHODS: The studied materials were composed of a visible-light-curing monomer mixture (Bis-GMA and TEGDMA or HEMA) and micrometric, nanometric or a mixture of both sizes hydroxyapatite particles as a reinforcing filler. Filler particles were modified with a coupling agent (citric, hydrosuccinic, acrylic or methacrylic acid or silane). The hydrolytic stability of the evaluated materials was studied through total elution and water-uptake tests. Percent net-mass variation was daily monitored and analyzed as a function of time. Mechanical performance was examined through flexural properties and Vickers hardness. Morphological surface changes were observed with scanning electron microscopy. ANOVA statistical analysis was performed (P<0.05). RESULTS: In general, the use of HEMA instead of TEGDMA did not substantially worsen the composite quality. Dental composites containing only nanometric particles of hydroxyapatite as a filler are unsuitable for clinical performance. Midway-filled composite resins loaded with micro-HAP particles, coated with citric, acrylic or methacrylic acid displayed low percent elution and water-uptake values. Mechanical properties were similar or even superior to those measured for silane treated particles. SIGNIFICANCE: More research is needed to further improve the interaction of nano-HAP particles with the polymeric matrix, either as a single filler or, preferentially, mixed with micro-HAP, that will allow to increase the total loading of reinforcing filler and, hence, to improve the mechanical properties.     

Impedance of rough capacitive electrodes: the role of surface disorder

The interfacial impedance of solid electrodes in the absence of Faradaic reactions usually deviates from purely capacitive behaviour; this effect is enhanced on rough electrodes. We present a qualitative experiment showing that capacitance dispersion on solid electrodes is due to surface disorder (i.e. heterogeneities on the atomic scale) rather than roughness (i.e. geometric irregularities much larger than those on the atomic scale).     

Vibrational study of adsorbed phosphate ions on rhodium single crystal electrodes

The adsorption of H₂PO₄^? ions was studied on low Miller index rhodium single crystal electrodes by in situ FTIR spectroscopy. It is found that for Rh(1 0 0) and Rh(1 1 0), H₂PO₄^? ions are the major species at low potentials, but at higher potentials, some of the H₂PO₄^? ions undergo a potential induced deprotonation and probably there is a mixture of H₂PO₄^? and HPO₄^2? ions. On Rh(1 1 1) the deprotonation starts at very low potentials and at higher potentials the H₂PO₄^? is fully converted to HPO₄^2?. The behavior of the band center and of the band intensity with the applied potential was also analyzed. It is found that the adsorption increases from 0.08 V vs. a Pd–H₂ electrode up to 0.5 V and then it decreases when the OH starts to be adsorbed.     

An alternative sinus floor elevation procedure: trephine osteotomy

Today, the sinus floor elevation procedure is not only being used on a routine basis, but clinicians are reporting high success rates. The sinus floor graft has become an important option in the treatment of the edentulous posterior maxilla, where vertical bone height is less than ideal. A review of maxillary sinus floor elevation as an integral part of restoring the posterior maxillary is discussed. The related anatomy of the area and current osteotomy techniques are reviewed. This article describes a trephine osteotomy, which is an alternative technique to the existing lateral antrostomy approach currently being used.