Rigidity, retention, and resistance of titanium versus double taper light root canal posts: An in vitro evaluation.

Aim: to evaluate and compare the physical properties of titanium posts and double taper (DT) light posts. Materials and Methods: Sixty posts (30 titanium post and 30 DT light post) were selected and divided into three groups. In Group I: Ten posts of each type were subjected to a three-point bending test. In Group II: 20 posts extracted maxillary central incisors were restored with ten posts of each type and subjected to tensile loading. In Group III: 20 posts extracted maxillary central incisors were restored with ten posts of each type and subjected to compressive loading at an angle of 135°. Results: The results showed that DT light posts were significantly less rigid (P <0.001), more retentive and significantly less resistant to fracture (P <0.001) as compared to titanium posts. Conclusion: It is suggested that although the DT light post system does not completely fulfill the requirements claimed by manufacturer but it would meet the requirements to combat the physiological forces operating in the oral cavity.

A comparative evaluation of the fracture resistance of endodontically treated teeth with compromised intra radicular tooth structure using three different post system.

Intra-radicular loss of tooth structure in endodontically treated teeth poses a challenge. Available methods for treatment are cast post-core, intra-radicular resin reinforcement using composite resin followed by placement of prefabricated metal/fibre post (glass or carbon).This study is an attempt to investigate the validity of treatment of such teeth using above methods and evaluate which post system is best suited for rehabilitation. Thirtysix endodontically treated anterior teeth were prepared by uniformly removing intra-radicular tooth structure from buccal, lingual, mesial & distal surfaces such that only 0.75mm-1mm remained. Twelve teeth were subsequently restored with cast metal post & core, 12 with intra-radicular resin reinforcement followed by prefabricated titanium post (Luminex post system) & 12 with intra-radicular resin reinforcement followed by glass fibre post (Luscent Anchor post system). Statistical analysis used was t-test. There was no statistically significant difference between the 3 post systems, but it was observed that cast post & cores caused more apical & oblique fractures, rendering the teeth unrestorable. Teeth restored with intra-radicular resin reinforcement & placement of titanium or glass fibre post failed with root fractures limited to the coronal aspect along with dislodgement of post. Intra-radicular resin reinforcement offers advantages like preventing the metal display of the post through the thin dentinal wall, reinforcement of the thin walled teeth & comparable fracture resistance to cast post and core.

Effects of resin cements on hardness and thickness around titanium post: an intraradicular assessment

The purpose of this study was to evaluate hardness (indicator for polymerization) and thickness of two types of resin cement at coronal, middle and apical level of tooth root canal. Ten extracted maxillary incisors were instrumented and post space was prepared for cementation of titanium post. Samples were divided into two groups and each group was cemented either of the two types of resin cements; Panavia F [dual-cured (PF)] and Rely X Luting 2 [self-cured (RL)]. The teeth were longitudinally sectioned; hardness and thickness was measured using Vickers hardness tester and a microscope (Leica DMLM). SEM observations along the cement line at the 3 different root levels were performed. Statistical analysis was performed to test significance of differences in hardness and thickness of the two types of cement (t-test; p= 0.05) and at different levels of the same type (one-way ANOVA followed by multiple comparison; p= 0.05). Significant difference of hardness was found at the apical level between the two groups and between the coronal and apical level of PF (p0.05). Moreover, voids were more obvious within the dual-cured group of cement. Dual-cured resin cement was found to be less polymerized than self-cured type at apical level. Increased thicknesses of resin cements in comparison to post space size were observed in both groups. Use of metallic post with resin cements needs further evaluation.

Influence of post types and sizes on fracture resistance in the immature tooth model / 대한치과보존학회지

The purpose of this study was to determine the effect of post types and sizes on fracture resistance in immature tooth model with various restorative techniques. Bovine incisors were sectioned 8 mm above and 12 mm below the cementoenamel junction to simulate immature tooth model. To compare various post-and-core restorations, canals were restored with gutta-percha and resin core, or reinforced dentin wall with dual-cured resin composite, followed by placement of D.T. LIGHT-POST, ParaPost XT, and various sizes of EverStick Post individually. All of specimens were stored in the distilled water for 72 hours and underwent 6,000 thermal cycles. After simulation of periodontal ligament structure with polyether impression material, compressive load was applied at 45 degrees to the long axis of the specimen until fracture was occurred. Experimental groups reinforced with post and composite resin were shown significantly higher fracture strength than gutta-percha group without post placement (p < 0.05). Most specimens fractured limited to cervical third of roots. Post types did not influence on fracture resistance and fracture level significantly when cement space was filled with dual-cured resin composite. In addition, no statistically significant differences were seen between customized and standardized glass fiber posts, which cement spaces were filled with resin cement or composite resin individually. Therefore, root reinforcement procedures as above in immature teeth improved fracture resistance regardless of post types and sizes.

A STUDY ON THE FRACTURE STRENGTH OF TEETH RESTORED WITH A CARBON FIBER POST UNDER CYCLIC LOADING / 대한치과보철학회지

In the restoration of endodontically treated teeth, carbon fiber post was recently introduced. The purpose of this in vitro study was to investigate the fracture strength of teeth restored with a preFabricated carbon fiber post in comparison with teeth restored with a prefabricated titanium post & custom cast gold post after cyclic loading in the different environment. A total of 30 recently extracted human central incisors of similar dimension with crowns removed were used. All teeth were placed into acrylic blocks and every steps for post and core fabrication were made according to manufacture s instruction. The post length and core dimensions were standardizd. All teeth were divided into 6 groups 1) carbon fiber post / atmosphere, 2) titanium post / atmosphere, 3) gold post / atmosphere, 4) carbon fiber post / wet, 5) titanium post / wet, 6) gold post / wet. Carbon fiber post and titanium post were cemented in place using resin cementt and cores were fabricated with Ti-Core. Custom cast gold post was made from Dur clay pattern resin and cemented using resin cement, too. All specimens were thermocycled 10,000 times. After 50,000 cyclic loading, failure strength was measured using Instron testing machine. KruskalWallis test followed by Mann-Whitney test was used to compare the mean fracture strength. Results were as follows 1. All specimens showed lower fracture strength in wet environment after cyclic loading than in atmosphere condition, but did not reveal a significant difference. 2. There was no significant difference between carbon fiber post specimen and titanium post spec imen in the same environment. 3. Gold cast post specimen showed significant different greater fracture strength than those of others in the same environment. 4. Carbon fiber post specimen showed no root fracture.