Bond strength of composite resin luting cements to fiber-reinforced composite root canal posts.

J Contemp Dent Pract. 2007;8(6):17-24

Authors: Le Bell-Rönnlöf AM, Lahdenperä M, Lassila LV, Vallittu PK

AIMS: The aim of this study was to compare the attachment of different composite resin luting cements to a fiber-reinforced composite (FRC) post with a semi-interpenetrating polymer network polymer matrix. METHODS AND MATERIALS: Six different brands of composite resin luting cement stubs were applied on the surface of FRC post material and light-cured for 40 seconds. Shear bond strengths of luting cement stubs were measured using a universal testing machine. RESULTS: The differences in shear bond strengths between the cements were not statistically significant. CONCLUSION: All of the tested composite resin luting cements provided acceptable attachment to the tested FRC post. The tested FRC post material is suitable to use with different composite resin luting cements.

PMID: 17846667 [PubMed - indexed for MEDLINE]

Application of a pre-impregnated fiber-reinforced composite in the fabrication of an indirect dowel-core.

J Oral Sci. 2007 Jun;49(2):179-82

Authors: Tanoue N, Nagano K, Shiono H, Matsumura H

The root canal space prepared for a foundation restoration is often elliptic or too large, and an unintentionally prepared undercut is sometimes detected. This article presents a dental laboratory technique to reconstruct an endodontically treated tooth using a pre-impregnated fiber-reinforced composite (FRC) system instead of a conventional fiber post. Particular attention was paid to increase the volume of the fiber in the root canal, and care was taken to achieve adequate primary laboratory polymerization of the matrix monomer. This simple technique is useful in the fabrication of an FRC dowel core with increased fiber content. (J. Oral Sci. 49, 179-182, 2007).

PMID: 17634733 [PubMed - in process]

Fiber-reinforced composite substructure: load-bearing capacity of an onlay restoration and flexural properties of the material.

J Contemp Dent Pract. 2006 Sep 1;7(4):1-8

Authors: Garoushi SK, Lassila LV, Tezvergil A, Vallittu PK

AIM: The aim of this study was to determine the static load-bearing capacity of composite resin onlay restorations made of particulate filler composite (PFC) with two different types of fiber-reinforced composite (FRC) substructures. In addition, flexural properties of the material combination and the effect of polymerization devices were tested. METHODS AND MATERIALS: Specimens were prepared to simulate an onlay restoration, which consisted of 2 to 3 mm of FRC layer as a substructure (short random and continuous bidirectional fiber orientation) and a 1 mm surface layer of PFC. Control specimens were prepared from plain PFC. In Group A the specimens were incrementally polymerized only with a hand-light curing unit for 40 s, while in Group B the specimens were post-cured in a light-curing oven for 15 min before they were statically loaded with a steel ball. Bar-shaped test specimens were prepared to measure the flexural properties of material combination using a three-point bending test (ISO 10477). RESULTS: Analysis of variance (ANOVA) revealed all specimens with a FRC substructure have higher values of static load-bearing capacity and flexural properties than those obtained with plain PFC (p<0.001). CONCLUSION: The load-bearing capacity of all the specimens decreased after post-curing and water storage. Restorations made from a material combination of FRC and PFC showed better mechanical properties than those obtained with plain PFC.

PMID: 16957785 [PubMed - indexed for MEDLINE]

An in vitro assessment of prefabricated fiber post systems.

J Am Dent Assoc. 2006 Jul;137(7):1006-12

Authors: Teixeira EC, Teixeira FB, Piasick JR, Thompson JY

BACKGROUND: The authors conducted a study to characterize the in vitro retention, fracture and light transmission behavior of four different fiber-reinforced resin-based composite root canal posts. METHODS: The authors divided 44 teeth into four groups according to the type of post they would receive: parallel fiberglass posts, double-tapered fiber quartz posts, tapered fiberglass posts and two different types of parallel fiberglass posts. They prepared teeth and cemented posts with dual-cured resin cement. After the specimens aged, the authors conducted pull-out tests. For fracture testing, they loaded posts at 45 degrees in a universal testing machine. They determined load-to-fracture values and relative stiffness. They measured percentage of light transmission by means of a light microscope coupled with a spectrometer. RESULTS: Both tapered posts showed lower retention than did the parallel posts. Scanning electron microscropic analysis indicated that more cement adhered to the surfaces of the parallel fiberglass post than to those of the tapered fiberglass post. All posts demonstrated some plastic behavior, with the double-tapered fiber quartz post being stiffer than the others. CONCLUSION: Parallel fiber-reinforced composite posts showed better retention than did tapered posts when a dual-cured resin-based cement was used. Translucent prefabricated posts have limited light transmission. CLINICAL IMPLICATIONS: Parallel prefabricated fiber posts luted with dual-cured resin-based cement seem to be suitable for clinical application in endodontically treated teeth that require post-and-core restoration, showing good retention and acceptable fracture resistance.

PMID: 16803828 [PubMed - indexed for MEDLINE]

The evaluation of the carbon fiber post system on restoration of teeth defect in children.

Chin Med J (Engl). 2006 May 20;119(10):809-13

Authors: Zhang XH, Wang XZ

BACKGROUND: Post and post-core systems are used to restore extensively damaged teeth. Among these systems, cast alloy post and core, prefabricated threaded alloy post and prefabricated simple alloy post are most frequently applied in China nowadays. In Europe and North America a combined application of the fiber post, resin-core and crown has been applied to restore seriously destructed teeth with satisfactory results in recent years. This study was intended to evaluate the clinical effect of carbon fiber post system on restoration of child anterior tooth defect after root canal therapy, based on 3 - 5 years' observation. METHODS: One hundred and six children with incompletely established occlusion were observed and followed for an average of 42 months (ranging from 36 to 60 months). Eighty-five upper teeth and forty-one lower teeth were restored with carbon fiber post system and composite jacket crown. Periodic check-up was conducted for periodontal condition and restoration effect. RESULTS: One hundred and twenty-one (96.2%) restorations were successful. Four jacket crowns (3.0%) were lost. One tooth (0.8%) had slight gingival inflammation. Tooth root or post fracture and gingival stain were not observed. X-ray showed there was no obvious change in aspects including the width of periodontal membrane, the density of alveolar bone and the height of alveolar ridge crest. CONCLUSIONS: Carbon-fiber post system can satisfy the clinical requirements of young patients who have residual anterior crown and root caused by trauma or caries, and have incomplete occlusion and have completed root canal therapy. This system helps realize good esthetic result for patients and easy practice for dentists. Carbon fiber post is safe and convenient, especially for sick children.

PMID: 16732982 [PubMed - indexed for MEDLINE]

Removal resistance of glass-fiber and metallic cast posts with different lengths.

J Oral Sci. 2006 Mar;48(1):15-20

Authors: Braga NM, Paulino SM, Alfredo E, Sousa-Neto MD, Vansan LP

This study evaluated the strength required to remove glass-fiber and metallic cast posts with different lengths. Sixty endodontically treated canines were included and their roots were embedded in acrylic resin after discarding the crowns. Samples were randomly assigned to 3 groups according to the post length (n = 20): I- 6 mm, II - 8 mm and III- 10 mm. Each group was divided into 2 subgroups based on the post material (n = 10): A- glass fiber or B- metallic cast. Post-space was prepared with Fibrekor Post Kit attached to a parallelometer. In subgroup A, prefabricated glass fiber posts from Fibrekor Post Kit were utilized. In metallic post group (subgroup B), an impression of post space was obtained, followed by casting. All posts were luted with Panavia F cement. A universal testing machine determined the force required to dislodge each post. ANOVA analysis indicated significant differences (P < 0.01) among post length. Tukey test showed that posts with 10 mm-length showed higher resistance on removal than posts with 6 mm-length. Posts with 8 mm-length did not exhibit difference when compared to 6 and 10 mm posts. No significant differences (P > 0.05) were observed between the tested post materials. It was concluded that the type of post did not influence the removal resistance and that posts with 10 mm-length required greater force to be dislodged.

PMID: 16617196 [PubMed - indexed for MEDLINE]

A review of the management of endodontically treated teeth. Post, core and the final restoration.

J Am Dent Assoc. 2005 May;136(5):611-9

Authors: Cheung W

BACKGROUND: The clinical decision as to whether an endodontically treated (ET) tooth requires a post and a crown poses a challenge to dental practitioners. The author conducted a review of the principles for the use of post and core and the newer materials such as ceramic and fiber-reinforced posts. TYPES of STUDIES REVIEWED: Using a MEDLINE search and resulting cross-references, the author selected original research articles and previous review articles on the topic of ET teeth, as well as that of post and core. RESULTS: The author reviewed the principles for the use of posts in terms of when it is necessary to use a post, different types of posts, various post materials and designs. He also reviewed the criteria and technique for post space preparation and post cementation. Finally, he discussed the principles of core buildup, as well as options for the final restorations. CLINICAL IMPLICATIONS: The author provides a review of the principles for the use of post and core, crowns and the different materials available today to help clinicians make a clinical decision based on sound evidence.

PMID: 15966648 [PubMed - indexed for MEDLINE]

Post concepts are changing.

J Am Dent Assoc. 2004 Sep;135(9):1308-10

Authors: Christensen GJ

Use of post-and-core restorations has changed markedly in the past several decades. Current use and research supports techniques using tooth-colored, fiber-reinforced resin-based composite posts or titanium alloy posts cemented with resin cement, followed by resin-based composite build-ups. Although fiber-reinforced resin-based composite posts appear to be very promising, long-term clinical observation is needed. I have made suggestions about when to use posts, what type of post to use and how to use them.

PMID: 15493395 [PubMed - indexed for MEDLINE]

Performance of high-speed dental handpieces subjected to simulated clinical use and sterilization.

J Am Dent Assoc. 1999 Sep;130(9):1301-11

Authors: Leonard DL, Charlton DG

BACKGROUND: The authors investigated the performance of nine commercially available high-speed air-turbine dental handpieces subjected to 1,000 simulated clinical uses and sterilizations. METHODS: Six new handpieces from each of nine different models were subjected to simulated clinical use with a custom-made handpiece wear tester and then autoclaved. Ten parameters related to clinical performance (longevity, power, turbine speed, fiberoptic transmission, eccentricity, noise, chuck performance, visibility angle, interocclusal clearance and water coolant spray pattern) were measured at baseline and after 250, 500, 750 and 1,000 use/sterilization cycles. RESULTS: Power, turbine speed, eccentricity and noise performance were statistically analyzed using one-way analysis of variance and Turkey post hoc pairwise comparison tests at the .05 significance level. At baseline, significant differences were found between models for all of these parameters. In general, from baseline to 1,000 cycles, the handpieces exhibited greater eccentricity and reduced fiberoptic performance. Longevity data analyzed by using Gehan's generalized Wilcoxon test for comparison of survival distributions (alpha = .05) revealed significant differences between the handpiece models. CONCLUSIONS: The results of this study indicate that no handpiece model is superior to the others in all parameters evaluated. All models evaluated can be expected to perform for at least 500 clinical use/sterilizations, or approximately one year, if properly maintained. CLINICAL IMPLICATIONS: Clinicians need to be able to identify handpieces that can withstand repeated heat sterilization without loss of performance or longevity. The results of this study will aid clinicians in selecting handpiece models that meet their needs.

PMID: 10492537 [PubMed - indexed for MEDLINE]

Recombinant human bone morphogenetic protein-2 promotes wound healing in rat periodontal fenestration defects.

J Dent Res. 1997 Aug;76(8):1460-70

Authors: King GN, King N, Cruchley AT, Wozney JM, Hughes FJ

Although there is considerable interest in the use of bone morphogenetic protein (BMP) to promote periodontal regeneration, little is known of its effects on the early stages of wound healing. The aim of this study was to investigate the effects of recombinant human bone morphogenetic protein 2 (rhBMP-2) on an early stage of post-operative wound healing and following complete healing (10 and 38 days, respectively) in a rat model of periodontal regeneration. The buccal aspects of molar roots were carefully denuded of their periodontal ligament through a bony window created in the mandibles of Wistar rats under general anesthesia. After the root surfaces were acid-conditioned, a 10-microL quantity of 50 microg/mL rhBMP-2 in a collagen gel solution was placed into the surgically created defect in test animals; in controls, either a 10-microL quantity of only collagen gel was received, or the defect was untreated. Animals were killed 10 days or 38 days after surgery and the tissues processed for histological examination. Transverse 5-microm sections were stained for the identification of new bone, cementum, and collagen fiber formation. In the 10-day study groups, new bone formation over the second molar and beyond the defect was significantly increased in the test group (p < 0.02), although there was no evidence of increased ankylosis. RhBMP-2 stimulated more than twice the area of cementum growth coronally compared with controls (712 +/- 286 microm2 and 258 +/- 57 microm2, respectively). Connective tissue attachment, including the number and width of collagen bundles, was similar in both test and controls. Complete healing without any evidence of ankylosis had occurred in all animals 38 days post-operatively, and no significant differences were observed between test and control groups. In conclusion, a single dose of rhBMP-2 increased the rate of normal intramembranous bone formation and selectively enhanced cementum formation coronally during early wound healing. However, the finding that rhBMP-2 induced bone formation at some distance from the defect suggests the importance of developing a suitable delivery system to maintain the concentration of BMP-2 at the site of implantation for potential therapeutic use.

PMID: 9240382 [PubMed - indexed for MEDLINE]

Immunolocalization of fibronectin during reparative dentinogenesis in human teeth after pulp capping with calcium hydroxide.

J Dent Res. 1996 Aug;75(8):1590-7

Authors: Yoshiba K, Yoshiba N, Nakamura H, Iwaku M, Ozawa H

Exposed dental pulp is known to possess the ability to form a hard-tissue barrier (dentin bridge). The exact mechanisms by which pulp cells differentiate into odontoblasts in this process are unknown. Fibronectin has been demonstrated to play a crucial role in odontoblast differentiation during tooth development. This study tested the hypothesis that fibronectin is involved in the initial stages of replacement odontoblast differentiation and reparative dentin formation. We observed its immunohistochemical localization during dentin bridge formation in human teeth, after pulp was capped with calcium hydroxide [Ca(OH)2]. One day after the capping, precipitation of crystalline structures was observed at the TEM level in association with cell debris at the interface between the superficial necrotic zone and underlying pulp tissue. This layer of dystrophic calcification showed positive reaction for fibronectin, and pulp cells appeared to be closely associated with this layer, seven to ten days post-operatively. At 14 days, an alignment of cells, some of which were elongated and odontoblast-like, was observed adjacent to the fibronectin-positive irregular matrix. Between the cells, corkscrew fiber-like fluorescence was visible. At 28 days, the irregular fibrous matrix was followed by the formation of tubular dentin-like matrix lined with odontoblast-like cells. Therefore, it would seem that fibronectin associated with the initially formed calcified layer might play a mediating role in the differentiation of pulp cells into odontoblasts during reparative dentinogenesis, after pulp was capped with Ca(OH)2.

PMID: 8906128 [PubMed - indexed for MEDLINE]

Quantitative diameter analysis of lingual nerve axons in man.

J Dent Res. 1986 Jul;65(7):1016-9

Authors: Heasman PA, Beynon AD

Previous studies on axon counts and fiber-diameter spectra in lingual nerves have been carried out only on animal models. This study reports an histological investigation on a series of 20 lingual nerves removed post mortem from human subjects. The results show wide variation in the myelinated fiber counts--a variation which does not appear to be related to the ages of the subjects. When the results are compared with those of a previous study (Heasman and Beynon, 1983), it is seen that the lingual nerve:inferior dental nerve ratio of axon counts is not a consistent index. The fiber-diameter spectrum for the human lingual nerve is characterized by a bimodal curve with the more pronounced peak in the small-diameter fiber range.

PMID: 3458751 [PubMed - indexed for MEDLINE]