Cornelis H. Pameijer

Nonvital Tooth Bleaching: A Review of the Literature and Clinical Procedures

Tooth discoloration varies in etiology, appearance, localization, severity, and adhesion to tooth structure. It can be defined as being extrinsic or intrinsic on the basis of localization and etiology. In this review of the literature, various causes of tooth discoloration, different bleaching materials, and their applications to endodontically treated teeth have been described. In the walking bleach technique the root filling should be completed first, and a cervical seal must be established. The bleaching agent should be changed every 3-7 days. The thermocatalytic technique involves placement of a bleaching agent in the pulp chamber followed by heat application. At the end of each visit the bleaching agent is left in the tooth so that it can function as a walking bleach until the next visit. External bleaching of endodontically treated teeth with an in-office technique requires a high concentration gel. It might be a supplement to the walking bleach technique, if the results are not satisfactory after 3-4 visits. These treatments require a bonded temporary filling or a bonded resin composite to seal the access cavity. There is a deficiency of evidence-based science in the literature that addresses the prognosis of bleached nonvital teeth. Therefore, it is important to always be aware of the possible complications and risks that are associated with the different bleaching techniques.

The Effectiveness of Manual and Mechanical Instrumentation for the Retreatment of Three Different Root Canal Filling Materials

The aim of this study was to compare the effectiveness of the Mtwo R (Sweden & Martina, Padova, Italy), ProTaper retreatment files (Dentsply-Maillefer, Ballaigues, Switzerland), and a Hedström manual technique in the removal of three different filling materials (gutta-percha, Resilon [Resilon Research LLC, Madison, CT], and EndoRez [Ultradent Products Inc, South Jordan, UT]) during retreatment. Ninety single-rooted straight premolars were instrumented and randomly divided into 9 groups of 10 teeth each (n = 10) with regards to filling material and instrument used. For all roots, the following data were recorded: procedural errors, time of retreatment, apically extruded material, canal wall cleanliness through optical stereomicroscopy (OSM), and scanning electron microscopy (SEM). A linear regression analysis and three logistic regression analyses were performed to assess the level of significance set at p = 0.05. The results indicated that the overall regression models were statistically significant. The Mtwo R, ProTaper retreatment files, and Resilon filling material had a positive impact in reducing the time for retreatment. Both ProTaper retreatment files and Mtwo R showed a greater extrusion of debris. For both OSM and SEM logistic regression models, the root canal apical third had the greatest impact on the score values. EndoRez filling material resulted in cleaner root canal walls using OSM analysis, whereas Resilon filling material and both engine-driven NiTi rotary techniques resulted in less clean root canal walls according to SEM analysis. In conclusion, all instruments left remnants of filling material and debris on the root canal walls irrespective of the root filling material used. Both the engine-driven NiTi rotary systems proved to be safe and fast devices for the removal of endodontic filling material.

Retention of parallel-sided titanium posts cemented with six luting agents: An in vitro study

PURPOSE This in vitro study compared the effectiveness of 6 luting systems on the retention of prefabricated titanium posts. MATERIAL AND METHODS A total of 120 single-rooted teeth were sectioned at the cementoenamel junction and treated endodontically. Roots were mounted in copper cylinders, and prefabricated, parallel-sided titanium posts were cemented according to the manufacturers instructions. Two resin-ionomer hybrid cements and 2 resin cements were tested with corresponding dentin bonding agents. A glass ionomer cement was also tested, and zinc-phosphate cement served as the control. Samples were tested in an Instron universal testing machine to catastrophic tensile failure. RESULTS Advance cement with Prime and Bond systems was found to be statistically more retentive than all other groups tested (P < .05). Cement It with Bond It and Permalute with Permalute Primers A and B systems demonstrated significantly greater retention than Ketac Cem cement, Resinomer with One-Step system and zinc-phosphate cement (P < .05). There was no statistically significant difference among Ketac Cem cement, Resinomer with One-Step system, and zinc-phosphate cement.

Reaction of Rat Subcutaneous Connective Tissue to a Mineral Trioxide Aggregate–based and a Zinc Oxide and Eugenol Sealer

INTRODUCTION The purpose of this study was to evaluate the subcutaneous connective tissue reaction in rats to a mineral trioxide aggregate (MTA)-based endodontic sealer Fillapex (Angelus, Londrina, PR, Brazil) and compare it with Grossman sealer (Farmadental, Buenos Aires, Argentina). METHODS Sterile medical-grade silicone tubes containing the test materials were implanted in 24 Wistar rats. After 10, 30, and 90 days, the animals (n = 8 per period) were euthanized, and the implants along with their surrounding tissues were dissected, fixed, and processed for histologic evaluation. A 4-category evaluation system was used to evaluate the microscopic observations. The tissue response on the lateral walls of the silicone tubes was used as the negative control. The data were analyzed for statistical significance using the Wilcoxon signed rank, Kruskal-Wallis, and Dunn tests. RESULTS Fillapex showed a severe tissue reaction for all 3 observation periods. Grossman sealer showed similar features after 10 and 30 days, but the reaction decreased slightly after 90 days. In contrast, the negative controls did not show adverse reactions in any sample of the 3 time periods. After 10 and 30 days, no statistically significant differences were found between Fillapex and Grossman sealer (P > .05); however, the difference was significant after 90 days (P < .05). For all experimental periods, there were statistically significant differences between both Fillapex and Grossman sealer and the negative controls (P < .05). CONCLUSIONS It was concluded that both MTA-Fillapex and Grossman sealer remained toxic to subcutaneous tissues in rats after 90 days.

A Review of Luting Agents

Due to the availability of a large number of luting agents (dental cements) proper selection can be a daunting task and is usually based on a practitioners reliance on experience and preference and less on in depth knowledge of materials that are used for the restoration and luting agent properties. This review aims at presenting an overview of current cements and discusses physical properties, biocompatibility and other properties that make a particular cement the preferred choice depending on the clinical indication. Tables are provided that outline the different properties of the generic classification of cements. It should be noted that no recommendations are made to use a particular commercial cement for a hypothetical clinical situation. The choice is solely the responsibility of the practitioner. The appendix is intended as a guide for the practitioner towards a recommended choice under commonly encountered clinical scenarios. Again, no commercial brands are recommended although the author recognizes that some have better properties than others. Please note that this flowchart strictly presents the authors opinion and is based on research, clinical experience and the literature.

Micro-computerized tomographic analysis of radicular and canal morphology of premolars with long oval canals

OBJECTIVE The aims of this in vitro study were to measure root and canal diameters, root and canal diameter ratios, mean taper of the root canal and of each root canal section, and radicular wall thickness at different levels in premolars with long oval root canals. STUDY DESIGN Thirty human premolars, with single long oval canals were selected for this study. The specimens were analyzed with micro-computerized tomography. The cross-sections corresponding to 1, 2, 3, 4, 5, 7, 9, 11, and 13 mm from the radiologic apex were analyzed to measure the mesiodistal (MD) and buccolingual (BL) diameters of the canals and the thickness of the root and the walls. The BL/MD ratios of the canal (DeltaC) and the root (DeltaR) diameters were calculated, as was as the mean taper in both a BL and an MD dimension. Multiple logistic regression analyses were performed with a level of significance of P = .05. RESULTS At all levels of analysis, the BL diameter was greater than the MD diameter for both the canal and the root. Generally, DeltaC and DeltaR increased coronally. Buccal and lingual wall thicknesses were greater than mesial and distal at all levels. Canal diameters at 1 mm from the apex were >0.30 mm in the shorter-oval diameter and >0.40 mm in the longer-oval diameter. In all root segments the BL taper was greater than the MD taper. CONCLUSIONS An oval canal anatomy was frequently present even in the most apical sections of the root canals. A high correlation was established between the shape of the root canal and the corresponding root.

Efficacy of the NaviTip FX Irrigation Needle in Removing Post Instrumentation Canal Smear Layer and Debris in Curved Root Canals

INTRODUCTION This study evaluated the effectiveness of the NaviTip FX (Ultradent Products Inc, South Jordan, UT), a 30-gauge brush-covered irrigation needle, in removing debris and smear layer in vitro. METHODS Forty mesio-buccal maxillary and mandibular first molar root canals with 20 degrees to 30 degrees curved roots were randomly divided into four groups (n = 10). The irrigation protocol after cleaning and shaping was as follows: NaOCl/EDTA/nonbrushing (NaED) group: passive use with 5.25% NaOCl followed by 17% EDTA and saline; EDTA/brushing (EDBr) group: passive use with 5.25% NaOCl followed by left and right manual rotary up and down brushing using 17% EDTA and a saline rinse; EDTA/FileEze (Ultradent Products Inc)/brushing (EDFEBr) group: same as EDBr, however, with FileEze; and control group (CG): a standard 30-gauge NaviTip irrigation needle used passively. The roots were split longitudinally and the canals examined in a scanning electron microscope. Debris and smear layer were recorded at 1, 5, and 10 mm from the working length (WL) using a three-step scoring scale and 300-mum square grid. Mean scores were calculated and statistically analyzed (p < 0.05) between and within groups. RESULTS Comparison between groups revealed that at all evaluation levels EDBr and EDFEBr groups were significantly cleaner (p < 0.05) than NaED and CG, with no significant difference between them. Comparison within groups did not show significant differences (p > 0.05). All groups showed significantly better smear layer removal (p < 0.05) at 5 and 10 mm from the WL. The EDBr group exhibited no significant differences (p > 0.05) between the three evaluation levels. CONCLUSION In moderately curved root canals, a NaviTip FX used with 5.25% NaOCL and 17% EDTA solution with manual brushing as well as the same method augmented by FileEze was the most effective cleaning protocol.

A modified dilatometer for determining volumetric polymerization shrinkage of dental materials

A modified mercury dilatometer is described where any change in the volume of the sample is registered every 0.5 s as a change of the mercury height in the capillary, which is measured electronically instead of by the naked eye. The device is relatively low in cost and enables measurements to be made on samples regardless of their shape or size. Four different light-curing dental materials - Amelogen (Ultradent Dental Products, South Jordan, UT, USA), Z250 (3M/ESPE, Minneapolis, MN, USA), Permaflo (Ultradent) and Filtec flow (3M/ESPE) - were initially tested. From the results it was concluded that with this modified dilatometer reproducible measurements, with a measurement error (residual standard deviation) of less than 0.027% and an average coefficient of variation of less than 1.22%, could be obtained. Thus, the instrument is particularly suitable for the study of light-curing dental resins.

Clinical and radiographic evaluation of a resin-based root canal sealer: an eight-year update.

INTRODUCTION This retrospective clinical and radiographic study evaluated the 8-year outcome of one-visit endodontic treatment of root canals filled with gutta-percha and a methacrylate resin-based sealer (EndoREZ). METHODS From an initial sample size of 180 patients, subsequently 145 and 120 patients were evaluated after 14-18 months and 5 years, respectively. Of the remaining patient pool of 120 patients evaluated after 5 years, 112 patients with 212 root canals responded to the 8-year recall. The outcome of treatments was assessed on the basis of clinical and radiographic criteria. Endodontic success was rated on the basis of absence of clinical symptoms, the presence of a normal or slightly widened periodontal ligament space, and absence or substantial reduction in size of preexisting periradicular radiolucencies. Teeth that did not meet these criteria were considered endodontic failures. RESULTS The root canals had been adequately filled to the working length in 90 teeth (80.35%) and were short in 19 instances (16.96%). None of the roots showing apical extrusion of the sealer immediately postoperatively had radiographic evidence of the sealer in the periradicular tissues after 8 years. At recall, all patients were comfortable and free of clinical symptoms. A life table analysis showed a cumulative probability of success of 86.5% after 8 years, with a 95% confidence interval of 79.0-92.0. CONCLUSIONS The results of this retrospective clinical and radiographic study suggest that the tested methacrylate resin-based sealer used in conjunction with gutta-percha cones performed similarly to conventional endodontic sealers during a period of up to 8 years.

Subcutaneous Connective Tissue Reaction to Methacrylate Resin–based and Zinc Oxide and Eugenol Sealers

INTRODUCTION An evaluation was made of the connective tissue reaction in rats after subcutaneous implantation of methacrylate resin-based sealers (EndoREZ [Ultradent Products, Inc, South Jordan, UT] with a polymerization accelerator and RealSeal [Sybron Dental Specialties, Orange, CA]) and Pulp Canal Sealer (Sybron Dental Specialties), a zinc oxide and eugenol-based sealer used as the control. METHODS Silicone tubes containing the test materials were implanted in 24 Wistar rats. Solid silicone rods of the same size served as the negative controls. After 10, 30, and 90 days, the animals (n = 8 per period) were euthanized and the implants with surrounding tissues dissected and processed for routine histological evaluation. A four-category evaluation system was used to measure and record the microscopic observations according to the thickness of a fibrous capsule, the vascular changes, and the various types of inflammatory cells. RESULTS Initially, a severe inflammatory reaction was observed of the soft tissues in direct contact with both EndoREZ/Accelerator and Real Seal. The severity decreased over time and was resolved at the end of the experiment. Pulp Canal Sealer showed a severe tissue reaction for all observation periods. The negative controls showed an initial mild to moderate inflammatory reaction. After 30 days, healthy fibrous connective tissue was observed, which increased over time. After 10 days, no statistically significant differences between the experimental groups were observed. After 90 days, EndoREZ and RealSeal were statistically significantly less toxic than Pulp Canal Sealer (p > 0.05). CONCLUSIONS After 90 days, both methacrylate resin-based sealers were considered biologically acceptable when implanted in subcutaneous connective tissues of the rat. Pulp Canal Sealer remained toxic for the duration of the study.