Fiber Post Removal: Comparative Study Using a New Post Concept

Objectives: To evaluate the time required to remove endodontic posts made of quartz and glass fibers, and compare them to a new glass fiber post designed for easy removal on the basis of efficiency and tooth damages. Methods: 40 human single-rooted teeth were treated endodontically and randomly assigned to four fiber posts groups: 1) was restored with Premier#90 (Innotech); 2) with DT#2 Lightpost (Dentsply); 3) with Unicore#3 (Ultradent); 4) with a special, soft-cored “S” glass fiber post ER-Prosthetic#3 (Overfibers). An impression of the canal was taken prior post cementation. The posts were luted with Panavia F and adhesive (Kuraray). All the specimens were mounted in a dental simulation unit to reproduce the difficulty of clinical conditions. The fiber posts were removed using a diamond bur /Gates and Largo reamer combination. The teeth were examined radiographycally 2 times seeking for cement, fiber composite debris and tooth damage. After post removal, another impression of the canal was taken for each tooth to evaluate the canal enlargement. Then, the specimens were fractured and observed microscopically. Results: No significant differences were found among the conventional posts (groups 1-3) as regards removal time and dental tissue loss (Kruskal-Wallis, alpha=0.05). The new soft-core concept applied to the ER-Prosthetics allowed a mean rank removal time significantly lower (P=0.001) than the mean rank of group 1-3 posts (Dunn's test). The canal enlargement was significantly lower with ER posts. Root perforation occurred in groups 1 to 3, but none was recorded in group 4. Conclusion: Removal of posts avoiding dental tissue loss is a difficult task when performed in simulated clinical conditions. A new post type conceived to be removed safely in a short time was very effective to reduce the removal time without tooth damages. Further studies will be necessary to validate this new concept

Fatigue failure and success rate of lithium disilicate table-tops as a function of cement thickness

Purpose: Under thin, partial coverage restoration the proper cement thickness to be clinically employed still remains an issue. The aim of this study was to determine the failure and success rates of simplified lithium disilicate occlusal veneers as a function of cement thickness. The null hypothesis was that cement thickness has no effect on the fatigue resistance. Methods: Sound human molars were severed in a plane parallel to the occlusal surface to create a flat dentin surface surrounded by enamel edges. Forty-five occlusal veneers 1.0 mm thick (IPS e.max CAD LT) were luted to the teeth with Multilink Automix resin cement, creating 3 experimental groups (n=15) with cement thicknesses of 50, 100, and 200 µm. The restorations were fatigue-cycled using a ball mill machine containing zirconia and stainless steel spheres. Twelve 60 min cycles were performed. Survival statistics were applied to “failure” and “success” events, comparing the three groups using a log-rank Mantel– Cox test and a log-rank test for trends (alpha = 0.05). Results: The failure and success rates were not significantly influenced by cement thickness (P = 0.137 and P = 0.872, respectively); thus, the null hypothesis was accepted. However, when log-rank test for trends was applied to failure events, the tendency to have less failures with increasing thicknesses was found statistically significant (P = 0.047). Conclusions: The cement thickness within the range adopted here did not have a significant effect on the failure or success rate of lithium disilicate occlusal veneers when exposed to randomized impact stresses generating fatigue phenomena

Effect of root canal preparation, type of endodontic post and mechanical cycling on root fracture strength

Objective: To evaluate the impact of the type of root canal preparation, intraradicular post and mechanical cycling on the fracture strength of roots. Material and Methods: Eighty human single rooted teeth were divided into 8 groups according to the instruments used for root canal preparation (manual or rotary instruments), the type of intraradicular post (fiber posts-FRC and cast post and core-CPC) and the use of mechanical cycling (MC) as follows: Manual and FRC; Manual, FRC and MC; Manual and CPC; Manual, CPC and MC; Rotary and FRC; Rotary, FRC and MC; Rotary and CPC; Rotary, CPC and MC. The filling was performed by lateral compactation. All root canals were prepared for a post with a 10 mm length, using the custom # 2 bur of the glass fiber post system. For mechanical cycling, the protocol was applied as follows: an angle of incidence of 45 degrees, 37 degrees C, 88 N, 4 Hz, 2 million pulses. All groups were submitted to fracture strength test in a 45 degrees device with 1 mm/min cross-head speed until failure occurred. Results: The 3-way ANOVA showed that the root canal preparation strategy (p<0.03) and post type (p<0.0001) affected the fracture strength results, while mechanical cycling (p=0.29) did not. Conclusion: The root canal preparation strategy only influenced the root fracture strength when restoring with a fiber post and mechanical cycling, so it does not seem to be an important factor in this scenario

Evaluation of temperature increase during in-office bleaching

ABSTRACT The use of light sources in the bleaching process reduces the time required and promotes satisfactory results. However, these light sources can cause an increase in the pulp temperature. Objective The purpose of the present study was to measure the increase in intrapulpal temperature induced by different light-activated bleaching procedures with and without the use of a bleaching gel. Material and Methods A human maxillary central incisor was sectioned 2 mm below the cementoenamel junction. A K-type thermocouple probe was introduced into the pulp chamber. A 35% hydrogen peroxide bleaching gel was applied to the vestibular tooth surface. The light units used were a conventional halogen, a hybrid light (only LED and LED/Laser), a high intensity LED, and a green LED light. Temperature increase values were compared by two-way ANOVA and Tukey´s tests (p<0.05). Results There were statistically significant differences in temperature increases between the different light sources used and between the same light sources with and without the use of a bleaching gel. The presence of a bleaching gel generated an increase in intra-pulpal temperature in groups activated with halogen light, hybrid light, and high intensity LED. Compared to the other light sources, the conventional halogen lamp applied over the bleaching gel induced a significant increase in temperature (3.83±0.41°C). The green LED unit with and without gel application did not produce any significant intrapulpal temperature variations. Conclusion In the present study, the conventional halogen lamp caused the highest increase in intrapulpal temperature, and the green LED caused the least. There was an increase in temperature with all lights tested and the maximum temperature remained below the critical level (5.5°C). The addition of a bleaching gel led to a higher increase in intrapulpal temperatures

Elemento di supporto e rinforzo per protesi dentali o restauri coronali.

Abstract A supporting or strengthening element (1) for dental prostheses or crown restorations made of a composite material consisting of a matrix (2) in which is embedded at least one solid phase (3) appropriately distributed in it, has a total length divided into at least three different sections (4, 5, 8), namely an apical section (4), a crown section (8) and an intermediate section (5); the sections (4, 5, 8), preferably equal in length, have uniform flexural and/or torsional rigidity obtained by a combination of different local geometries and different flexural and/or torsional elasticity moduli. The different elasticity moduli of the individual sections (4, 5, 8) are obtained by a suitably differentiated distribution of the solid phases (3) in the body of the matrix (2)

Pharmacologic therapy of cranio-cervico-mandibular disorders. Review of the literature

The recommended treatments of craniomandibular disorders (CMD) are drug therapy, physiotherapy, relaxation procedures, occlusal therapy with and without splint. The purpose of this study is to carry out a survey of the literature on drug therapy in patients affected by CMD. It is essential to recognize the cause of pain (muscular or articular) and the phase of disorder (acute or chronic) in order to establish an adequate pharmacological protocol for each type of CMD. Non-steroidal anti-inflammatory drugs (NSAID) are generally accepted for treatment of internal derangement and myofacial pain, sometimes in association with benzodiazepine

Pharmacologic therapy of cranio-cervico-mandibular disorders. Review of the literature

The recommended treatments of craniomandibular disorders (CMD) are drug therapy, physiotherapy, relaxation procedures, occlusal therapy with and without splint. The purpose of this study is to carry out a survey of the literature on drug therapy in patients affected by CMD. It is essential to recognize the cause of pain (muscular or articular) and the phase of disorder (acute or chronic) in order to establish an adequate pharmacological protocol for each type of CMD. Non-steroidal anti-inflammatory drugs (NSAID) are generally accepted for treatment of internal derangement and myofacial pain, sometimes in association with benzodiazepine