Evaluation of Two Post Core Systems Using Two Different Methods (Fracture Strength Test and a Finite Elemental Stress Analysis)
Eskitşcioğlu, Belli, and Kalkan
Inactivation of the Antibacterial Activity of Iodine Potassium Iodide and Chlorhexidine Digluconate Against Enterococcus faecalis by Dentin, Dentin Matrix, Type-1 Collagen, and Heat-Killed Microbial Whole Cells
Portenier, Haapasalo, Ørstavik, Yamauchi, and Haapasalo
Effect of Three Different Sealers on the Sealing Ability of Both Thermafil Obturators and Cold Laterally Compacted Gutta-Percha
Schäfer and Olthoff
Periapical Lesion Development in Rats Inhibited by Dexamethasone
Metzger, Klein, Klein, and Tagger
Effect of Sonic and Ultrasonic Retrograde Cavity Preparation on the Integrity of Root Apices of Freshly Extracted Human Teeth: Scanning Electron Microscopy Analysis
Gondim, Jr., Figueiredo de Almeida Gomes, Randi Ferraz, Teixeira, and José de Souza-Filho
Evaluating IL-2 Levels in Human Pulp Tissue
Anderson, Dumsha, McDonald, and Spitznagel, Jr.
Evaluation of Two Post Core Systems Using Two Different Methods (Fracture Strength Test and a Finite Elemental Stress Analysis)
Gürcan Eskitşcioğlu, DDS, PhD, Sema Belli, DDS, PhD, and Mustafa Kalkan, DDS, PhD
The aim of this study was to compare a fiber composite laminate (FCL) post core and a conventional cast post core system by using two different methods. The first method was a conventional fracture strength test, and the second was a finite elemental stress-analysis method (FEM). For the conventional fracture strength test, 20 extracted, human upper, central incisors were used. The teeth were decoronated, treated endodontically, and restored with two post core systems. After embedding the samples in resin blocks, a loading force was applied to the teeth at a crosshead speed of 5 mm/min at an angle of 45 degrees to the long axis of the tooth. The data were recorded, and the results were compared by using the Mann-Whitney U test. There was no statistically significant difference between the two post systems (p > 0.05)
For FEM analysis, a pseudo three-dimensional model of a maxillary central incisor, theoretically restored with either a cast post or an FCL, was used. The analysis was performed by using the structural analysis program (SAP90). FEM analysis showed that stress was accumulated within the cast post core system, and transmission of stress to supportive structures and the tooth was low. This is an advantage for tooth and supporting tissues. When the FCL post core system was evaluated by FEM, the results indicated that this system transferred stress to supportive structures and the tooth while stress accumulation within the post system was low. This is an advantage for the restoration but disadvantage for the supporting tissues.
Inactivation of the Antibacterial Activity of Iodine Potassium Iodide and Chlorhexidine Digluconate Against Enterococcus faecalis by Dentin, Dentin Matrix, Type-1 Collagen, and Heat-Killed Microbial Whole Cells
Isabelle Portenier, DDS, Hanna Haapasalo, DDS, Dag Ørstavik, DDS, PhD, Mitsuo Yamauchi, DDS, PhD, and Markus Haapasalo DDS, PhD
The antibacterial activity of chlorhexidine digluconate and iodine potassium iodide on Enterococcus faecalis A197A was tested in the presence of dentin, dentin matrix, dentin pretreated by EDTA and citric acid, collagen, and heat-killed cells of Enterococcus faecalis and Candida albicans.
Medications were preincubated for 1 h with each of the potential inhibitors and tested for their antibacterial activity against E. faecalis, strain A197A. Surviving bacteria were sampled after 1 and 24 h of incubation.
Dentin matrix and heat-killed microbial cells were the most effective inhibitors of chlorhexidine, whereas dentin pretreated by citric acid or EDTA showed only slight inhibition. Dentin and skin collagen showed some inhibition at 1 h but not after 24 h. Iodine potassium iodide was effectively inhibited by dentin, dentin matrix, and heat killed microbial cells. Skin collagen and dentin pretreated by EDTA or by citric acid showed little or no inhibitory effect on iodine potassium iodide.
Different components of dentin are responsible for the divergent patterns of inhibition of the antibacterial activity of chlorhexidine digluconate and iodine potassium iodide. Chemical treatment of dentin before applying the medication into the root canal may alter the antibacterial effect of the medication.
Effect of Three Different Sealers on the Sealing Ability of Both Thermafil Obturators and Cold Laterally Compacted Gutta-Percha
Edgar Schäfer, Priv-Doz Dr med dent and Gudrun Olthoff, cand med dent
The purpose of this study was to assess the seal obtained in straight and curved root canals filled with either laterally compacted gutta-percha or Thermafil obturators. Each technique was used in combination with three different sealers (RSA RoekoSeal, AH Plus, AH 26). Thermafil obturators were also used without sealer, resulting in a total of 14 test groups of 16 teeth each. Sixty teeth served as positive or negative controls. Included in the study were 142 extracted teeth with straight and 142 with curved root canals. All canals were enlarged up to size 40. After obturation, all roots were placed in India ink for 48 h and rendered transparent to measure the maximum linear dye penetration. Canals filled with Thermafil obturators had significantly more extrusion of filling material than canals filled by lateral compaction (p < 0.01). Thermafil without sealer showed significantly greater dye penetration compared with all other groups both in straight and curved canals (p < 0.05). As long as a sealer was used, the seal obturated with Thermafil was equivalent in terms of dye penetration to lateral compaction. There were no statistical differences in the mean apical dye penetration among the three sealers. The differences between the dye penetration in straight and in curved canals were insignificant for all groups (p > 0.05). Under the conditions of this study, Thermafil obturators achieved seals comparable to lateral compaction, as long as a sealer was used.
Periapical Lesion Development in Rats Inhibited by Dexamethasone
Zvi Metzger, DMD, Hagay Klein, DMD, Abraham Klein, PhD, and Michael Tagger MS, DMD
Bone resorption is one of the hallmarks of inflammatory periapical lesions and is mediated by cytokines. Recent insights into the immunobiology of these lesions indicate that pharmacological modulation of their bone resorbing activity may be possible. Periapical lesions were induced in rats by occlusal exposure of the pulps of their lower first molars. The size of the resulting lesions was followed-up and evaluated by image analysis of their radiographs. The lesions increased with time, and the average area of their radiographic images reached 2.18 (+0.33) mm2 by day 21. Systemic dexamethasone treatment (0.5 mg/kg, every third day) inhibited the growth of the periapical lesions, which reached an average area of 1.63 (+0.30) (p < 0.01). These results support the hypothesis that bone resorption in periapical inflammatory lesions may be pharmacologically down regulated.
Effect of Sonic and Ultrasonic Retrograde Cavity Preparation on the Integrity of Root Apices of Freshly Extracted Human Teeth: Scanning Electron Microscopy Analysis
Eudes Gondim, Jr., DDS, MS, Brenda Paula Figueiredo de Almeida Gomes, DDS, MS, PhD, Caio Cesar Randi Ferraz, DDS, MS, PhD, Fabrício Batista Teixeira, DDS, MS, PhD, and Francisco José de Souza-Filho, DDS, MS, PhD
Sonic and ultrasonic root-end preparation devices permit the preparation of conservative and straight cavities. However, microfractures and marginal chipping can occur due to the vibratory action of such instruments. The purpose of this study was to evaluate the effect of retrograde preparations by using sonic and ultrasonic tips on the integrity of root-end surfaces. Eighty, human anterior teeth were grouped according to size and treated as follows: treatment 1: root-end resection (RR) and root-end cavity preparation (RP) with KIS ultrasonic retrotip; treatment 2: RR and RP with Satelec S12/90 (no diamond coating) ultrasonic retrotip; treatment 3: RR and RP with a diamond-coated retrotip attached to a sonic device (Sonics); treatment 4: RR and RP with Satelec S12/90D (diamond coated) ultrasonic retrotip. The root-end surface topographies were assayed by means of polyvinyl-siloxane impressions and epoxy resin replicas. SEM pictures of each sample were taken before and after preparation, and the images were evaluated by using an image processing and analysis system. The parameters evaluated were shape quality, presence of cracks, and marginal chipping. The results showed no statistically significant differences among anatomic groups, treatments, or tooth sizes (p > 0.05). Because treatment 3 removed more dental structure than the others did, its use on small teeth is inadvisable.
Evaluating IL-2 Levels in Human Pulp Tissue
Lisa M. Anderson, DDS, Thom C. Dumsha, MS, DDS, N. J. McDonald, BSc, BDS, and John K. Spitznagel, Jr., DDS, PhD